I can't buy license for fm23 version, it says inaccessible when I'm trying to do it
I've noticed that as well. I didn't receive any notification from Thanos about it, so I'm currently unaware of the reason. It could be a fastspring related issue or perhaps Thanos disabled it.
Either way, I don't know whether it's temporary or not; I've messaged him to ask, but it's been a long while since the last time I've had news. I'll let you know if/once I hear back.