I do not have a subscription and the 45-day period is over.
I deleted the license and tried again but I still can't activate.
I checked on the site if there was a version available, as for the alpha6 of 3DSmax. But I didn't see any.
It will only activate again if the trial period hasn't already been used. Which it has as you've mentioned. Unfortunately, your only option at this point is a subscription. As the betas were free whilst in development we decided to give users a "second go" at the software ie: 45 day trial. This was so they could try out the new features and if liked, a subscription would follow. But, not everyone wants to pay for things, myself included. Beer should be free in my opinion ;)
With that said though, there will be a free version for Cinema 4D. It will also be similar to the Alpha 6 version the Max users have access to. And also, it will be limited by its features. Again, like the 3ds Max Alpha. As to what will be in there I cannot say (I simply don't know) and when it will be released is still in the works.
It might be an idea to sign up for a newsletter as I'm sure this will be mentioned when released. You can add your email at the bottom of this link
https://corona-renderer.com/ ;)