The keys are automatically put into your account, so all you have to do is go to a subserver of your choice, do /key or click on the chest in spawn, and open your key!
Hey MaggiMix! As Noxid said above, if you own Immortal the monthly ancient key will automatically be redeemed and put into your keys (as if you bought them). These can be opened at the 'Treasure Chest' at the spawn of any subserver and be used for great loot! Question Answered/Thread Locked