> What software companies need to do is sell versions, where the life time of the version usefulness is actually limited... Can the same not be found for many software products?

Some of the enterprise software I've worked on has an option that functions this way. You pay for a specific version which is supported for a few years. You can keep using it forever but if you want to keep getting security updates or live support then you'll have to buy a newer version that is still in its support window.

Having said that, it seems like most businesses seem to prefer subscriptions.