When a cohort mapping reaches its end date, it will expire and be removed from the Moodle course (along with the relevant students).
In order to minimise disruption to students, it's always a good idea to check the unenrolment dates for the cohort are set to your specific requirements in advance of the mapping expiring.
Prior to using the Manage Mappings interface, you may wish to consider Understanding the Manage Mappings interface.
At this point, a new window will open up. This window will display a list of all of the courses that you have Teacher access to.
In the example shown above, there are default mappings only (an automatically created and applied mapping) but it is possible to have a user defined mapping (manually created).
To view all enrolled users including their unenrolment conditions, press the View Enrolled Users button.