We’ve been wrestling with this bug for years, but I finally decided to test it out so I might figure out what’s going on.
Here’s the scenario. Your customer has a credit card saved in their profile. You notice that the card has expired, so you click the “Credit Card” tab from the take payment screen. This allows you to see credit card info, update the expiration date and security code, and check the box that says, “Save for Future Use” before running the payment for processing.

Now, what would you expect, “Save for Future Use” to mean? Most rational folks would assume that Booker would save the changes you made to your customer’s credit card for use in the future. NOPE! Booker doesn’t save anything.
You end up thinking that Booker saved those changes, but it did not. So, just what does that little checkbox accomplish? Nothing, as far as I can tell. Well, maybe it does one thing: it lulls you into thinking you have updated your customer’s credit card info, when in fact you have not.