It used to be you bought a key to unlock it permanently, but nowadays it ties your license to your Microsoft account. There’s a link to “unlock with a product key“, but I have no idea how you get one of those. I hate renting software rather than owning it, but also VS2019 is where I’m most productive so I put up with it.
This isn’t even the first time this has happened. I do most of my development on my desktop computer, sometimes I go long stretches without using my laptop. More than once I opened up my laptop on a flight to try and get some coding work done, but surprise, license is expired and I don’t have any connectivity to renew it. Absolutely ridiculous.