A dedicated Post Type to keep trace of your Payments
Payments
Custom Post Type
Saved Payments
Quick access to all payments from standard Admin interface
Basic Post Information
Standard information about the Author (the WP User who made the payment), the Page from the Payment were done and the current Payment Status.
Extra Information
All Custom Fields that you can collect from the form submission
All Payer Information provided by the gateway that could be different from the Author
Transaction Info
All Product Fields that customer bought through the payment
All Transaction Information (like Paypal) provided by the gateway that could change based on the kind of command