I don't think it is FREE... I believe the paradigm is this...
You still have to be on subscription, but now, instead of Altium working on and supporting only the CURRENT version, they will continue to support previous versions with bug fixes. And, you can continue to get fixes for previous version for up to 3 years as long as you are on subscription. At least that is how I read the release info.
I could be wrong. My latest subscription is about to expire shortly so I'll know soon.