Hi Stacey!
I did some checking for you, and while the balance on the gift card never expires, it cannot be exchanged
for cash. Because of this, I think I have an alternate suggestion (to leaving the card at the front desk) that may work in this situation.
Since you'd like to pay for your room charges via the gift card, the best bet will be to not leave it at the front desk, but to instead stop by the front desk either nightly, or on the night before your departure day. When you stop by there, let them know that you'd like to view your charges and make a payment. At that time, you can use your gift card to pay off any of the charges.
It's up to you if you'd like to do this nightly, a couple of times during the trip, or wait until the night before check out. But, be sure to do it before check-out day, as you don't want the charges to be placed on your credit card! Also, each resort type has a charging limit on your Key to the World card (Values: $500, Moderates: $1000, and Deluxes: $1500). Depending on where you're staying, you may need to check in if you approach the limit, so that your credit card isn't charged.
For more info on the Disney Gift cards, please visit their
FAQ page.
Hope this helps! If you need any more info, be sure to let me know!