The Sims 3: Date Night is a DLC that can be activated on The Sims' website. In order to activate this product:

1. Login on The Sims' website (www.thesims3.com) using your Origin login and password.
2. Under "My Page" menu hover over "My Account" and select "Redeem a Code".
3. Click "Redeem a Code"
4. Enter your code and select "Redeem"
5. Click on "Purchase History" LINK which will appear after activation. You can also navigate there through "Store" -> "My Store Account" -> "Purchase History".
6. Click "Download" link below the download icon. Your launcher wil start downloading your respective content.
7. After downloading, click "Install", which will appear below.
8. That's all, from now on you will own your DLC.