This is more of a "programmers" question, but felt that it was technical enough to belong on Stack Overflow instead.

I'm launching an application soon that will follow the shareware model of purchase. I've thought about implementing this in a few ways:

• Limited access to the application until they purchase
• Full access to the application but expires after 30 day, requiring them to purchase to retain utility.
• Full access to the application indefinitely, but with a 10-15 second pop-up box on start-up asking them to register -- like mIRC does (or used to do).

The method of authentication will be web-based. I'll provide them with an authentication key and they'll put it in the application. Whenever the application boots up, it'll check my web service and determine whether the application is genuine or not. This isn't my question.

My question is: Is there a preferred method of implementation? I'd like to piss off the users as little as possible, but I'd also like to get paid for my work.