Implementing Expiration Dates in an application?

Question

I\'d like to put an expiration date in some software I made. Obviously

psuedocode:

if time() > xxx: exit()

All someone has to do he

Answer 1

The solution doesn't need to be perfect, it just has to be annoying enough to the user so he won't try to game the system.

You could calculate the aboslute value's difference and make sure that it is smaller than X days. In that way, they would need to always keep their clock within X days. Which no one would ever do forever.