ORIGINAL SINS OF A SOLAR EMPIRE. NEVER REGISTERED. unsure of version but think its v1.00

ok so wen i perchesd the game from walmart thare was no cd key it wasn't on the back of the book an there was no card. i am an expereanced gamer both on concole an computer i got the game wen it first came out. so i inventoryed everything  down to taking the cover out of the case an looking on that agen found nuthing. i tryed to take it back to walmart an exchange it for a diforent one but walmart wouldnt take it back. so iv ben playing it offline without up dates an now wen my dad fineds a file on the disk that should be the cd key it wont register can any one help?