Serfent

I just purchased a Sins of a Solar Empire game from Ebay. it installed fine and everything but i dont know where the CD Key is, theres a Silver sticker with something that looks like a Serial Key but it has a german or something letter on it and it doesn't even seem to be long enough for a Serial Key, i got a CD Case and no Box. Game installed fine, just i cant put a CD Key in for Ironclad so that i can actually play multiplayer... the guy said he buys and resells games so he doesn't know where