and does each donation come with a 12 or 13 or 14 digit code ?
The box owner has the MAC on the box. With them Avovès all that is left needed by the box owner is the code they bought from you, so yes give it to them.
Unless there is some sorta different way resellers do it. I know some keep that code so they can shut down the client by changing their MAC, for what ever reason I do not know.
If they pay you in full, then there should be no reason not to give them the code, and now you would have to, if they are gonna be able to use their Avov box after nov 1.
Not like before, where they did not need the code.