This is a very small project that should be delivered in no more than a few hrs. In brief:
1: User signs up after payment
2: info is saved on mysql db
3: User queries db to register software. If info exists, then it generates registration key
4: User enters this info on sw, sw confirms it's there, then accepts registration
(admin can search, generate keys / mass mail / send single email).
Here are the more detailed specs:
[url removed, login to view]