Why does my Sims 3 (Origin) product Key not work?

I believe in some cases it can take origin  up to an hour (maybe longer) for the auto reg to show in your the sims3 account my page icons , also make sure you log in the sims 3 site with the same email and password you used for the origin account if you used two different email/password you may need to contact CS to assist with merging the accounts so try log out then back in using the origin email and password  to see if that will kick in the account being recognized 

FAQ http://answers.ea.com/t5/The-Sims-3/FAQ-Invalid-and-Used-Serial-Codes-amp-Games-not-showing-up-in/td-p/194028

if in the event you need to contact CS

1.https://help.ea.com/en/contact-us/
2.Click on the orange NEXT button
3.Select a platform
4.Click on the orange NEXT button
5.Select a topic and describe your problem in a few words
6.Click on the orange NEXT button
7.Click Chat Now to chat with a Game Advisor


guide on how to contact CS

http://answers.ea.com/t5/Beta-Archive/How-to-contact-a-Game-Advisor-using-the-new-EA-Help-page/td-p/2161281