Please tell me it's not the cell phone bill. I haven't bought an app yet because I don't know how the pay method happens, can I add in my own card to be charged?
When you purchase something from the Store, if you haven't purchased anything from Google Checkout, you'll be prompted to use a credit card, which will be stored for future purchases. It's very easy and secure. And, you have 24 hours to try out an app you purchase, and if you don't like it, then you can uninstall it and get your money refunded.