A virtual online currency that players of the Nexon Game publishing company spend hundreds of dollars in annually just to make themselves look better and play better... when chances are, they'll quit in 3 months time when they find out that items aren't permanent.
Player #1: Hey, I just got 90k NX!
Player #2: Well, aren't you the rich one! =D (Give me some!)
Player #1: I'm gonna get a new overall, a hat, a new weapon mask-over, a per...
** 90 Days Later **
Player #1: OMG I look like a freakin hobo.
Player #2: Did I not mention that items expire in 90 days?
--Player #1 has quit the game... permanently--