Django: How can I check the last activity time of user if user didn't log out?

You need to have the last_activity field in the user profile (or custom user model). This field will be updated on every request. To achieve this you need to have custom middleware:

profiles/middleware.py:

from django.utils import timezone

from myproject.profiles.models import Profile


class UpdateLastActivityMiddleware(object):
    def process_view(self, request, view_func, view_args, view_kwargs):
        assert hasattr(request, 'user'), 'The UpdateLastActivityMiddleware requires authentication middleware to be installed.'
        if request.user.is_authenticated():
            Profile.objects.filter(user__id=request.user.id) \
                           .update(last_activity=timezone.now())

Add this middleware in your setting file:

MIDDLEWARE_CLASSES = (
    # other middlewares
    'myproject.profiles.middleware.UpdateLastActivityMiddleware',
)

I know the question is old ... and surely it has already been solved ... but here is my contribution ... In new versions of django you can use:

"Session Time" -> Used in configuration file. "settings.py"

If the user closes the browser, the session ends and must be logged in again ...
SESSION_EXPIRE_AT_BROWSER_CLOSE = True

If the user does not close the browser, you can set a time limit for the session ...
SESSION_COOKIE_AGE = 60 * 60 

For "SESSION_COOKIE_AGE" if I remember correctly it's defined in seconds. You can see more here... Recommended reading is also django's own documentation about sessions...