If a BBPS account has been set up, you can enter credit card numbers into The Raiser's Edge, and they would be stored in BBPS in the appropriate circumstances. However, you would not be able to process credit cards via The Raiser's Edge without the use of a supported gateway, such as Blackbaud Merchant Services

Storage of credit card data without any intent on processing could be in violation of PCI Compliance.  If you are doing this, we suggest seeking the expertise of a Qualified Security Assessor (QSA) to ensure PCI Compliance at your organization.