[znpy]

Explain them that the software you sold him/her ten years ago is not the software you sell today.

But in the end, some people will just try and get free stuff. Just tell them that doing business with you has a price and that otherwise they can bring their business at someone else's shop.

[NameNickHN]

Yes, I did that and they accepted without comment. Interestingly enough, the total invoice that included some programming work was four figures. The update fee on the other hand was only $99.