Software, especially on Apple systems, can require perpetual updates to work correctly
Fwiw, Waves'entire WUP business (and now their attempts at a subscription model) only really works because of Apple. Simply because Apple keeps sh***ing on any kind of backwards compatibility regularly. Now, sometimes that might be for good reasons, sometimes it quite defenitely isn't. Just that Apple doesn't give a damn. So there we (Mac users) are, only living happily from autumn to autumn, just to see what things they will break with the next macOS update.
Sure, you don't need to update your OS all the time, but sometimes you do (or *really* want to for good reasons). Usually, you can skip at least every other OS update without running into any issues regarding other software updates, but things have gotten massively tighter during the last 2-5 years. Until then it was possible to run, say, the most recent Logic version on a macOS 4-5 version numbers behind. These days it's already down to "just the latest and second to latest" macOS'es. So, in case there's a certain fix or feature you'd really like to use, you will often have to update your OS before.
And that's the particular moment when Waves' evil plan starts to work. "Oh, you're updating macOS Catalina? We're so sorry, no way to run your V9 plugins anymore - but you can take advance of our great update plan!"
Not that this would be much different with some other companies (as in new OS versions requiring updated plugins), but some companies don't always charge you for updates. Waves does so all the time. Take U-He's most excellent Zebra 2 as an example (or their as excellent MFM2 delay machine). Free updates ever since they got released way over a decade ago, they'll always only be charging you for big version number updates (and some added features would defenitely be worth a big version number jump).
And then there's Windows. Which typically doesn't require you to update much software at all. Chances are that at least until the most recent version of Windows 10 (sort of different with Win 11 perhaps), you could still run a whole number of plugins released 20 years ago without them being updated. Number of this old plugins you could run on an actual macOS version: Exactly zero.
This very Apple behaviour has already made me lose lots of plugins. Tons of freeware but also things such as NI's B4, FM7, Pro-53, with Battery 3 to follow, which is actually causing me headaches already because I use that in each and every project and Battery 4 is an offense towards human intelligence. Upgrades don't help a lot, either, because older projects would not load properly anymore once a plugin is upgraded to a different version number (hence plugin ID). Sure, with Waves that's different because even the oldest plugins are still updated - but then: forced into WUP!
TL;DR: Use Macs and Waves plugins = recipe to get shafted!
And as this is about Waves plugins, I won't get into Apple's planned obsolescense obscenities - there's quite some more stories to be told.
Regarding Waves plugins, I personally just started deleting them already. The only thing I may keep for a while is their CR8 sampler, because there's really nothing like it on the market right now, but I hope this will change one day.