If you own the Steam Version of the base game, you will need to make sure it’s also registered on thesims3.com/Origin in order to be able to redeem it. The stuff pack will be on Origin and not Steam after redeeming so you will need to uninstall the Steam version of every Sims 3 game and install the Origin one instead. You can’t mix Steam and Origin.
oh, that is so easy Ivana, Steam gave you the game CD codes for your The Sims 3, just use that code to register on The Sims 3 website & Origin. But you have to say goodbye to steam version of your Sims
(you want to play offline that's the way to go smile) and best of all, you just have to register your base game codes on Origin, then purchase the sims 3 Town Life Stuff pack and cash out with $0 smile get it while you still can