If your database is on a network, I would suggest picking up the users network name. Match this against a table of users which will also include a date-logged-in field.
Then you could have a query or code which runs every time the database is open which checks the difference between their 2 dates (last-logged-in date and today). If the difference is greater than say 3 days (or whatever) then a message comes up and says they can't go any further and shuts the database.
I suppose you could have a status field as well that switches between yes/no and use that.
As you can tell, I thought up this just very quickly off the top of my head, and I'm not really awake yet!! but it'll give you an idea perhaps.
Col