Wyzant Student Loophole possibly?

So I have this one student on Wyzant who constantly takes off his credit card after each session (I do successfully submit the session before that though, so I think he would still get charged for it.) And then later I noticed he puts the card back on file….until our next session where he does the same thing.

Is there a loophole on student’s end where they can get away with not getting a charge on their credit card by doing this after each session?