This is the mid-July update Nelson was talking about in the last Devlog, and is the Release Override “Beta Testing” Package mentioned on the roadmap Trello for game access. The cap likely won’t be made public.
I’m assuming that the cap may be lowered as the game becomes more developed, and that a reasonable assumption may be that it could be 2,400 hours to start with, although it could be higher or lower than that.
If you already have access then you should still have access.
Until Devlog #024, the game has been distributed via a CD Key Package. This is just another type of distribution package, and in this case players will be able to play based on their playtime in U3.