You will need your id and a major credit card upon check-in. If the trip is already paid for, then they will swip it for charges to your room (room service, purchases in the parks, etc.). If it is not paid for, then they will charge your credit card the balance owed on the room. Your room key can be used for charging food, purchases, etc. throughout the parks. These charges will then appear on your regular credit card that was swiped at check-in. If you do not want to have your room key used as a charge card, make sure to inform the CM at check-in that you do not want charging capabilities on your room key. Also, unless you purchase separate park tickets, your park tickets will be put on your room key as well. If you do use your room key for charging capabilities, make sure to keep track of your purchases.