There's one particular post from Lunibook that I feel is worth calling special attention to, posted by WBL member Flambridge on late Saturday, November 5, 2011, the day after the closure was announced:
It all speaks for itself, though there's one thing I wanna discuss. According to this, LU had 2 million players, only 100,000 of which were paying subscribers. The 2 million figure is backed up by the official press release announcing the closure:
There's one other number for paying subscribers I've seen floating around the internet though, 38,000. The source for that seems to be Brick by Brick by David Robertson, which has a whole chapter on the development of LU. I own a copy, here's the relevant part:
It seems they meant a few months before the closure was announced (to both the players and developers) on November 4th, 2011, not a few months before the servers shut down (Midnight of January 30, 2012)... There'd have been no cautious optimism at that point, nor a staff to be even be optimistic, besides the few left to maintain the servers. So the 38,000 number probably comes from around the time F2P was launched in August 2011, maybe slightly before. F2P would have then been responsible for the rise from 38,000 subscribers to 100,000 subscribers + 1.9 million F2P players in the few months until it was axed on that morning in early November.