I've struggled a bit to understand the current Path Finder model. Certainly their previous one, which took a lot of heat, disabled the software when the subscription ended. I think they don't do that any longer. ForkLift won't be doing that.
But yeah, the new approach, which most people call subscription, does have more frequent payments for upgrades (usually annually) than the old days where we use to pay for upgrades when there was a new major version.
You pay for a version and can use it as long as you want (assuming backward compatibility with macOS version) ... if there are sufficient features and development in a subsequent release, pay the "upgrade" ("subscription") fee to get the new version... cancel subscription and repeat... not difficult to comprehend IMO ... very much like how software licensing used to work... I guess if they can keep you on the annual upgrade train, it amounts to an annual subscription ... but we do that with iPhone all the time ... pay until you don't want to, then jump off the PathFinder (or ForkLift) gravy train ...