Upvote:8
There are roughly two types of reservations with booking.com. The reservation which is paid upfront. In that case it's clearly stated when booking the accommodation. If so, then your friend's creditcard will be charged. The other type of booking is the one where you pay upon check-in or check-out. You're free to choose which payment method you use (off course only those accepted by the hotel). If you're not showing up, the hotel might charge your friend's creditcard though. Based on your description, your reservation would be payable upon arrival. You can thus pay with your own card.
If you're not sure if upfront payment applies to the booking, just give booking.com a call. In my experience, they're always happy to help.