Yes, if someone in your organisation leaves and they had access to Course+, you can quickly and easily reassign their licence to another user. Simply remove the departing user from the AccessCourse+ admin group so that they no longer have the permission to access Course+, and then you can add the new user to the admin group. The newly added user then takes the place of the departing user and takes up that licence instead.
For more information on how to add users to and remove users from the AccessCourse+ group, see Granting and revoking access to Course+.