You have a "fully up to date" product until an operating system upgrade breaks it or there's a security vulnerability that really does need to be patched.
Although I sold a small-time file manager shareware product for a number of years, I tend to agree that forever upgrades isn't a great model in general. Especially if sales are trailing off over time, I have zero incentive to provide updates/patches especially if some major change is needed. In my case, I decided that a significant upgrade would require major changes and it wasn't worth the effort. Not sure it would have been even with an upgrade fee but certainly wasn't absent one.
>You have a "fully up to date" product until an operating system upgrade breaks it
The amount of Windows executables that cannot work after upgrades is absurdly low, and is often obscure software that either relies on internal behavior or simply hasn't been tested and approved on newer versions by The Powers That Be. MacOS tends to be dreadful on backwards compatibility, but that's more due to Apple's clown-ish behavior when it comes to backwards compat. As for linux, well, welcome to LTS life.
> there's a security vulnerability that really does need to be patched.
So, for an extremely small minority of programs, it's a problem. Unless there's an RCE in FL Studio, you won't ever need to upgrade it. And unless FL Studio takes in unsanitized output from the outside... yeah, no, not a problem.
Buying a dollar for pennies always feels good, sure. However, using products of unsustainable businesses means you can't depend on it. For some products that's not a problem, for others it can become huge problem when you find yourself locked in maintaining old version of an OS or a companion software. The effect of not getting updates is very pronounced in professional or industrial software where to this day some people are forced to secure floppy disc supplies and deal with Windows XP.
In college we had a lab of really old PCs which run a very old version of AutoCAD because the school purchased that version and it wouldn't run on modern machines, I was told. There was another lab in similar situation with Adobe products.
After the subscription model raised to prominence, people get the latest version of the software and pay only as long as its useful for them. It's a win-win because the developer has the incentive to provide the best possible service in order to retain customers.
That’s really not about the business though. People hate on new versions all the time if a behavior or UI changed, this is old as the days of software.
Some software companies handle it better than others.
My wallet isn't here to pay for your company's inability to find a market.