The credit card companies (Visa, MC, etc) have come up with a set of rules that merchants have to follow, known as "PCI Compliance". One of the most important rules is that customer credit card information should never be saved (either in a website or in paper files) unless you have a certified secure storage system.
The Valued Websites system is not set up to store customer credit card information. You would need to pay thousands of dollars per year extra just on a secure hosting upgrade, and that’s just the beginning.
Instead, you should direct customers to your website’s payment page — the payment page is secure and it does not store credit card information, and it is PCI compliant. More on invoicing and payments.