Just bought Sims 4... Product Key not recognized

FIXED..
For those of you who downloaded the limited trial edition here is what to do:
FIRST: Uninstall the old trial edition.
SECOND: Install the game
THIRD: Ignore the product registration and click on the origin button at the top of the origin window.
FOURTH: Click "REDEEM PRODUCT CODE"

If you go straight to enter the product code, it doesn't work.

Scratch that. It asked me for the key again and it won't let me play. Looks like I'll be needing your help!

Have a look at this topic:
http://answers.ea.com/t5/The-Sims-4/FAQ-Serial-Codes-Game-Activation-and-Download-Issues/td-p/4228232