The code should be activated on the Warframe's site: https://www.warframe.com/promocode
In order to redeem the key:
Warning! Only one code of this type can be activated per account.
This is the perfect pack for a new player to get a quick start in Warframe. This pack offers the flexibility of choosing what you want based on how you like to play. It will open up your choice of Warframes, weapons, and equipment and allow you to more quickly advance in the game.