They are the serial codes with the game from my electronic receipt. I'm not sure if there is another product key/serial number somewhere that I should be using, but it's the only one I found and it also came with the messages that I should be receiving x, y, and z free when I register my game.
How many numbers does it have ? If it's 16 digits then it's for store content, 20 digits would be the serial code of the game
Did you not get an email with any codes ? Did you check your spam folder ?
Also check your purchase History: https://store.thesims3.com/purchaseHistory.html if anything was added there.
