Credit card details are stored in the system for 14 days after check-out.
If you want to you can add a message on how you use the card:
*SETTINGS->BOOKING PAGE->ADVANCED "Guest Details Header" - content will appear only on the booking page showing the upsell items and guest booking questions. It will appear at the top of the page under the property header information.
*SETTINGS->BOOKING PAGE->ADVANCED "Confirm Booking Button Message" - Text entered in this field will appear on the booking page in the area above the Confirm Booking button.