Bella had not promised anything. She was seventeen after all, she was allowed to use magic now, even if her particular brand of it went against the rules of the Wizarding World anyway.
"Fine" said Bella taking the card and regarding it. "How does it work? Cause it looks nothing like any money I've ever seen, and I once saw Muggle money, Rodolphus lifted it off a Hufflepuff last year."
She wasn't about to turn away money, in this place where she suspected the Black Fortune couldn't be accessed.
"Why do you care? Thats the only bit I still don't get"