diff --git a/openedx/features/course_duration_limits/access.py b/openedx/features/course_duration_limits/access.py
index b33d5d3c75..1e3515382c 100644
--- a/openedx/features/course_duration_limits/access.py
+++ b/openedx/features/course_duration_limits/access.py
@@ -3,13 +3,15 @@
 Contains code related to computing content gating course duration limits
 and course access based on these limits.
 """
+from __future__ import absolute_import
+
 from datetime import timedelta
 
+import six
 from django.utils import timezone
-from django.utils.translation import get_language, ugettext as _
-
-from student.models import CourseEnrollment
-from util.date_utils import strftime_localized
+from django.utils.translation import get_language
+from django.utils.translation import ugettext as _
+from web_fragments.fragment import Fragment
 
 from course_modes.models import CourseMode
 from lms.djangoapps.courseware.access_response import AccessError
@@ -20,7 +22,8 @@ from openedx.core.djangoapps.catalog.utils import get_course_run_details
 from openedx.core.djangoapps.content.course_overviews.models import CourseOverview
 from openedx.core.djangolib.markup import HTML
 from openedx.features.course_duration_limits.models import CourseDurationLimitConfig
-from web_fragments.fragment import Fragment
+from student.models import CourseEnrollment
+from util.date_utils import strftime_localized
 
 MIN_DURATION = timedelta(weeks=4)
 MAX_DURATION = timedelta(weeks=18)
@@ -34,7 +37,6 @@ class AuditExpiredError(AccessError):
     def __init__(self, user, course, expiration_date):
         error_code = "audit_expired"
         developer_message = u"User {} had access to {} until {}".format(user, course, expiration_date)
-        language = get_language()
         expiration_date = strftime_localized(expiration_date, EXPIRATION_DATE_FORMAT_STR)
         user_message = _(u"Access expired on {expiration_date}").format(expiration_date=expiration_date)
         try:
@@ -229,7 +231,7 @@ def course_expiration_wrapper(user, block, view, frag, context):  # pylint: disa
     # Course content must be escaped to render correctly due to the way the
     # way the XBlock rendering works. Transforming the safe markup to unicode
     # escapes correctly.
-    course_expiration_fragment.content = unicode(course_expiration_fragment.content)
+    course_expiration_fragment.content = six.text_type(course_expiration_fragment.content)
 
     course_expiration_fragment.add_content(frag.content)
     course_expiration_fragment.add_fragment_resources(frag)
diff --git a/openedx/features/course_duration_limits/admin.py b/openedx/features/course_duration_limits/admin.py
index fd391ab8f0..8da2910b60 100644
--- a/openedx/features/course_duration_limits/admin.py
+++ b/openedx/features/course_duration_limits/admin.py
@@ -3,16 +3,20 @@
 Django Admin pages for CourseDurationLimitConfig.
 """
 
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 from django.contrib import admin
 from django.utils.translation import ugettext_lazy as _
 
 from openedx.core.djangoapps.config_model_utils.admin import StackedConfigModelAdmin
+
 from .models import CourseDurationLimitConfig
 
 
 class CourseDurationLimitConfigAdmin(StackedConfigModelAdmin):
+    """
+    Admin for course duration limit
+    """
     fieldsets = (
         ('Context', {
             'fields': CourseDurationLimitConfig.KEY_FIELDS,
diff --git a/openedx/features/course_duration_limits/apps.py b/openedx/features/course_duration_limits/apps.py
index d88cc87209..a07f2d56ba 100644
--- a/openedx/features/course_duration_limits/apps.py
+++ b/openedx/features/course_duration_limits/apps.py
@@ -2,7 +2,7 @@
 Course duration limits application configuration
 """
 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 from django.apps import AppConfig
 
diff --git a/openedx/features/course_duration_limits/config.py b/openedx/features/course_duration_limits/config.py
index 9328d25fb4..8b4f264c79 100644
--- a/openedx/features/course_duration_limits/config.py
+++ b/openedx/features/course_duration_limits/config.py
@@ -1,15 +1,6 @@
 """
 Content type gating waffle flag
 """
-import random
-
-from django.dispatch import receiver
-from django.db import IntegrityError
-
-from experiments.models import ExperimentData, ExperimentKeyValue
-from student.models import EnrollStatusChange
-from student.signals import ENROLL_STATUS_CHANGE
-
 
 EXPERIMENT_ID = 11
 EXPERIMENT_DATA_HOLDBACK_KEY = 'holdback'
diff --git a/openedx/features/course_duration_limits/message_types.py b/openedx/features/course_duration_limits/message_types.py
index 3e6a77f52d..9cc8c73c57 100644
--- a/openedx/features/course_duration_limits/message_types.py
+++ b/openedx/features/course_duration_limits/message_types.py
@@ -1,6 +1,8 @@
 """
 Message types used for ACE communication by the course_duration_limits app.
 """
+from __future__ import absolute_import
+
 import logging
 
 from openedx.core.djangoapps.ace_common.message import BaseMessageType
diff --git a/openedx/features/course_duration_limits/models.py b/openedx/features/course_duration_limits/models.py
index 4a9b67b0e2..9feede4249 100644
--- a/openedx/features/course_duration_limits/models.py
+++ b/openedx/features/course_duration_limits/models.py
@@ -3,14 +3,14 @@ Course Duration Limit Configuration Models
 """
 
 # -*- coding: utf-8 -*-
-from __future__ import unicode_literals
+from __future__ import absolute_import, unicode_literals
 
 from django.conf import settings
 from django.core.exceptions import ValidationError
 from django.db import models
+from django.utils import timezone
 from django.utils.encoding import python_2_unicode_compatible
 from django.utils.translation import ugettext_lazy as _
-from django.utils import timezone
 
 from course_modes.models import CourseMode
 from lms.djangoapps.courseware.masquerade import (
diff --git a/openedx/features/course_duration_limits/resolvers.py b/openedx/features/course_duration_limits/resolvers.py
index d3d1e6a124..31c627cac3 100644
--- a/openedx/features/course_duration_limits/resolvers.py
+++ b/openedx/features/course_duration_limits/resolvers.py
@@ -2,23 +2,25 @@
 Resolvers used to find users for course_duration_limit message
 """
 
+from __future__ import absolute_import
+
 import logging
 from datetime import datetime, timedelta
 
-from course_modes.models import CourseMode
 from django.contrib.staticfiles.templatetags.staticfiles import static
 from django.db.models import Q
 from django.utils.timesince import timeuntil
 from django.utils.translation import ugettext as _
 from eventtracking import tracker
+
+from course_modes.models import CourseMode
+from courseware.date_summary import verified_upgrade_deadline_link
 from lms.djangoapps.experiments.utils import stable_bucketing_hash_group
 from openedx.core.djangoapps.catalog.utils import get_course_run_details
-from courseware.date_summary import verified_upgrade_deadline_link, verified_upgrade_link_is_valid
-
 from openedx.core.djangoapps.schedules.resolvers import (
     BinnedSchedulesBaseResolver,
     InvalidContextError,
-    _get_trackable_course_home_url,
+    _get_trackable_course_home_url
 )
 from track import segment
 
diff --git a/openedx/features/course_duration_limits/tasks.py b/openedx/features/course_duration_limits/tasks.py
index 2c6d86cb32..446428eafa 100644
--- a/openedx/features/course_duration_limits/tasks.py
+++ b/openedx/features/course_duration_limits/tasks.py
@@ -2,9 +2,12 @@
 Tasks requiring asynchronous handling for course_duration_limits
 """
 
+from __future__ import absolute_import
+
 import datetime
 import logging
 
+import six
 import waffle
 from celery import task
 from celery_utils.logged_task import LoggedTask
@@ -16,11 +19,9 @@ from edx_ace.message import Message
 from edx_ace.utils.date import deserialize, serialize
 from edx_django_utils.monitoring import set_custom_metric
 from opaque_keys.edx.keys import CourseKey
-from openedx.core.djangoapps.schedules.tasks import (
-    _annonate_send_task_for_monitoring,
-    _track_message_sent
-)
+
 from openedx.core.djangoapps.schedules.resolvers import _get_datetime_beginning_of_day
+from openedx.core.djangoapps.schedules.tasks import _annonate_send_task_for_monitoring, _track_message_sent
 from openedx.core.lib.celery.task_utils import emulate_http_request
 
 from . import message_types, resolvers
@@ -77,7 +78,7 @@ class CourseDurationLimitMessageBaseTask(LoggedTask):
             target_date = current_date + datetime.timedelta(days=day_offset)
             task_args = (
                 site.id,
-                unicode(course_key),
+                six.text_type(course_key),
                 serialize(target_date),
                 day_offset,
                 override_recipient_email,
diff --git a/openedx/features/course_duration_limits/tests/test_models.py b/openedx/features/course_duration_limits/tests/test_models.py
index fcc48d6348..fb5b22c083 100644
--- a/openedx/features/course_duration_limits/tests/test_models.py
+++ b/openedx/features/course_duration_limits/tests/test_models.py
@@ -18,7 +18,6 @@ from course_modes.tests.factories import CourseModeFactory
 from openedx.core.djangoapps.config_model_utils.models import Provenance
 from openedx.core.djangoapps.content.course_overviews.tests.factories import CourseOverviewFactory
 from openedx.core.djangoapps.site_configuration.tests.factories import SiteConfigurationFactory
-from openedx.core.djangoapps.waffle_utils.testutils import override_waffle_flag
 from openedx.core.djangolib.testing.utils import CacheIsolationTestCase
 from openedx.features.course_duration_limits.models import CourseDurationLimitConfig
 from student.tests.factories import CourseEnrollmentFactory, UserFactory