My custom apps are always supported and there are some fees associated with such support so for me, I have yet to say no to continued support as it's a good revenue source.

However one client wanted support for free and it took a few months to go over our agreements about the product. I can't reveal much more about that except we're back on track now.

As I don't have the full story all I can offer is that versions do die and it can upset the clients.
Bob