*Lifetime for the time the product/service is alive

If they end the thing, they can just pretend they did a rewrite and invalidate the current version/not develop it any further and maybe offer a migration discount (lol).
I'd prefer the model of "Buy version X for at least x years of feature updates and Y days of security updates".

In the past it didn't matter, because you had the whole file structure for the application when you purchased it. You either downloaded it in whole as an install file or archive, or you had it on the physical media that you purchased it on. Maybe there was a license you had to input or some other rudimentary DRM system, but you had that too. No remote access from the company, no forced additional downloads or internet connectivity, no phone home. So they could say whatever they wanted, but you actually had the product.

Now with media files that only play with proprietary tools that phone home, or applications that phone home, your computers are backdoored. And if you have a system that's backdoored, it's not really yours, it's just something you can access for now. That's what your Kindle is: a backdoored computer with an e-ink screen and proprietary software that can open proprietary files that other software isn't supposed to be able to open. Which is why no one should buy one.