Comment by fph

Yes, the free version can be used indefinitely.

The latest device you can use with full support is Sony Xperia 10 III, released in 2021. There have been no further releases; the project never really took off and unfortunately it seems that the OS is slowly dying. The Finnish company behind it, Jolla, had a joint project with Russia (Aurora OS), which I believe provided a good chunk of the funds via Rostelecom. With the war everything changed, and in 2021 they had to cut ties entirely with Russia for many reasons: embargos, and many people rightfully not wanting anything to do with "a Russian OS" on their phone. The company had to be "restructured" in 2023.