Best practices to "lock" a program after a certain amount of time?

[jagarock]

I want my program to function fully for a week. Then I want to lock it, and the user has to buy the full version and input a license key to continue using it.

How can this be done in a good way? Needs to be something so the user cannot just delete and reinstall the program for another free week of usage.

I guess one way would be to have the program communicate with a database on my servers. Lets say the program captures hardware ID, sends it to my database with a timestamp, then whenever the program runs it will check my DB if the free period is up.

Is this the only way though? Can it be done without throwing http requests around?

[InunoTaishou]

Saw this topic a couple of days ago in the example subforum