Well, there is a Redeem button, so why not use it. The Gift cards should be sold in $10, $25 and $50. Each giving a certain amount of energy depending on the card. Also when the card is redeemed the person who redeemed the code gets a free, 2 week elevator pass for the clockworks. Another idea is that when you redeem the code depending on the event that is on you could get some special costumes or accessories and the Elevator pass. And as a final note, it would have to be sold worldwide and not just in America because I want one too.
The Redeem Button is to acclaim prizes like a Prime Bombhead Mask.
You can simply use an Ultimate Game Card for energy which isn't only in America.