

Lifetime for security. Other features (new drivers…) you can pay for, but security is lifetime. You need to escrow enough money to provide this service or prove that nobody is using the OS.
All services required for use of the device are also lifetime - though they may charge a subscription price so long as that price is clear to the customer before the first sale and prices go up by inflation only. After 15 years they can drop the service if it is easy for a “normal user” to switch to a different subscription provider; and all source code required for someone “skilled in the art” to create and maintain their own service provider is publicly released under terms that allow modification and redistribution was released at least 5 years before killing their own service.
You are allowed to drop support for any protocol that is not latest recommended state of the art so long as you maintain what was recommended at time of release. If a newer protocol comes out you need not support it. (Which is to say you can be IPv6 only today, and if the internet switches to IPv12 in the future you don’t have to support that)
The above applies to anything network connected. OS, web browser, Security camera, thermostat…
I find it weird that every part time jobs tries to play off flexible scheduling as a perk. Their schedule isn’t flexible, they decide what shifts they want me to work. It might be better than factory work where you always work exactly the same shift or you must take vacation (or sick leave but they demand a doctor’s note) - but you can plan around that well in advance. Meanwhile every full time job I’ve had wasn’t factory work and so the expectation was "work any 8 hours per day, make sure you show up for the important meetings)