I have always thought what would make a really good pricing model for software, and after reading through Cabel’s post on Panic’s Dev Issues board, I think I agree with Cabel.
You buy Nova, and you keep it forever. You do not need to pay anything more for the software to keep working forever — it’s yours. In addition, you get one free year of feature and bug updates. After that year, you can pay a steeply discounted price to continue to receive another year of updates — but that is totally optional.
Maintenance is often the most challenging part of software development. Ensuring that the software keeps working/improving and remains bug-free after the initial version is shipped is the most time-consuming part.
I wish more companies did this. You buy, keep it forever at that major version. All future versions come at a cost, which users of the previous version get to buy at a discount.