Credits is the site intra-currency of GM2P.com, before you're going to buy stuff from the sellers on GM2P.com, you need to buy credits from GM2P.com first.
The purpose is to ensure the security of the transaction, if you meet any problems with the order you made, such as the seller didn't deliver the product, the product doesn't meet the description, you can apply for a refund in your account center at GM2P.com, our team will check it and help you out. The credits will automatically return to your account balance if the problem was caused by the seller, you don't need to contact the Bank or Third-party Payment Company to initiate dispute or refund request.
This will make shopping on GM2P.com very easily and convenient, you can handle many issues in your account center by this way.