Lost my Product Key

If you installed the game before, you can find your game ready in Origin. (and I believe you can find your product key in there as well)

If you did not install before, look an the booklets that come with the game. It's not on the box.
Nothing there, contact EA and prove you bought the game:
http://help.ea.com/en/contact-us/new/

WERE CAN I GET A PRODUCT KEY

With a copy of the game.