CCP treats plex as deferred income on their balance sheets. Plex represents a contract between the players and the company for 30 days of game time. While we buy and sell it for in-game currency, it only becomes real world revenue to them when someone redeems it for game time. Say, if there is $7 million total plex rolling around (this is a number I seem to recall) but only $1 million of it is redeemed in a year, CCP can only claim $1 million in revenue, and the rest is treated as a liability that is carried over until it’s used.