On your Adopia Account page click My Account

In the My Account Information popup window, under Billing Info click Update Credit Card.

In the Update Credit Card Details popup window enter your First Name, Last Name, Address, City, State, Zip, Billing Email, Phone, Credit Card Number, Credit Card Type, CVV and Card Exp. Date. 

When you are finished check the box that says "I authorize Adopia LLC to charge my credit card for monthly recurring." By checking this box it 

means that this will be the credit card that receives billing going forward.  

You can also update your credit card information by contacting an Adopia Support representative. 

 Send an Email: http://www.adopia.com/support.html