Made some headway into how the server side bit works and I can register the program without even patching it now, all I need to do is construct a proper response locally and spoof it (using fiddler or any other HTTP Interceptor out there)
I Reversed the way errors are done too
http://cdn.che.moe/woqbze.png
I attached the tool you can use to generate valid serial key responses and errors.
I'll eventually make a tool using FiddlerCore but I can't be bothered right now.