Final Fantasy XIV: A Realm Reborn Key
Info From The Humble Bundle Info Page:
THIS KEY CAN ONLY BE REDEEMED BY NEW USERS, IT CANNOT BE APPLIED TO ACCOUNTS THAT ALREADY OWN THE GAME FOR ADDITIONAL SUBSCRIPTION TIME. KEY CANNOT BE APPLIED TOWARDS FREE TRIAL ACCOUNTS MADE THROUGH STEAM.
To redeem your Final Fantasy XIV: A Realm Reborn key, you will need a free Square Enix account and the Final Fantasy XIV game client.
When you successfully register the game to your account for the first time, you will receive 30 days of non-recurring subscription game time, afterward you must purchase more game time in order to continue playing. If you already have the game registered to your account you cannot stack another key on top for more play time.