Proof?

[durf]

Probably the stupidest question ever, but how do I show my friend if my VB is legal?

[onehost]

Why do you think it is important for him to know. The important thing
is that you know it is legal, and not worry about it.

[Videx]

Just send him a copy of your last receipt. I mean, unless he thinks you're going to go to the trouble of forging one. If that's the case, tell him to report you and screw him.