One problem with time limited is that the user can adjust the PC clock. So you need other checks in your software to get around them doing that.
It will be much easier to use the suggestion by theDBguy, but put in a check to make sure they aren't deleting any using Access itself or by a little utility they've written. Often restricting the number of records in at least three tables is sufficient. Just weigh up how you could get around your own security and you're pretty well there. But if you come up against some propeller-head you are possibly wasting your time trying to do it with Access anyway.
It's all a bit of a game really, you just need to make sure you're on the winning side.