Verification System.

One of my programs requires payment from users.

It will work like the following:
1. They pay me
2. I send them the Application

But i want to prevent people from re-distributing it when It's been downloaded.. What's the best way to do this? I would like to create something the connects to a database, and when the users have payed, i create them/they create a user+Password and they use that to connect...

Does anyone know how to do this?
Like all my other thread, if you need any further information, just ask.

This has been asked a million times over here and else where. If you do some Google or VBF searches, you'll find plenty of information, and arguments, on the best methods.

That being said, there's no fool proof methods, but I'm sure you can find something that will suffice.

Can you give me some links please? I've searched, but can't find anything..