.

Hey, i'm from EU but there is no mention of region lock from what i can tell.

I think i can go first, it's up to you.

Here is what it says :

NOTE: 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.

Register a Square-Enix Account

Download Final Fantasy XIV: A Realm Reborn

So basically all you need is a new account or an account without the game. It gives you an entire month of gametime, starting as soon as you launch the game i believe.

Edit: Nevermind