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

Work off of the create date of one of the files you install.

this gives you a non-changing date to subtract from now to get the time the program has been installed. The only problem with this is when they re-install it. The easiest way to combat this is with a registry setting.