I have a website that works with a VB6 program I wrote.
When my software is installed, it gets authenticated by sending the website a key. This key is validated on the website and sent back to my software.
There are a two tasks that my website handles. The first is to give the buyer the software. Once he has downloaded it, the database is marked as downloaded. Next he returns to the site to validate the software and the key is validated. This transaction is recorded in the database too.
I have moved to a linux server so need it changed to PHP.