WP Theme Nulling? Question

Okay so I paid for a WP Theme that is GPL, which allows me to modify the code. And I paid for the theme and have the receipt and activation number. The thing about the theme is it limits how it works when the key is invalid. When the key is invalid, it shows 10 posts. If it's valid, it shows them all. It seems that it is coded so that it checks back with the developers server and verifies various details. It also works to disable it back to demo mode if it is installed on a second site. Quite an exhaustive system actually to be sure it's support license stays in tact. I'd like to fork the theme and change the design and layout which I can figure out perfectly, but I'm lost as far as this validation code. And it's spread through multiple files. Any suggestions on how I could begin to unravel this? Or should I just hire someone to code that part away?