So, is there an alternative to buying it again?

So I bought Sins in 2008 and have been playing it single player as vanilla ever since with no patches or anything, but because of that I never registered.  I recently came across some more people who play it and want to join in the multiplayer scene with them and probably buy Entrenchment also, but I never entered my key with Impulse or whatever, and have lost my case.  I have the cd, and the cardboard sleeve the case came in, but that's it. 

I can't find any way to contact them, so I was wondering if anyone here had an idea of what to do.  Obviously I hope to avoid buying it again.  And yeah I realize it looks like I'm just trying to con them out of a free cd key, but I'm not.

Thanks much.