Nexon
Commonly referred to as 'NX Cash' or just 'NX', the NEXON Cash system was one of the first systems to use the Virtual Asset Sales(VAS) model. The NEXON Cash system was first introduced in the Korean version of MapleStory. The NEXON Cash system allows users to purchase NEXON cash with real money.  The NX cash can be used to obtain virtual game items that other users normally wouldn't have. You can buy cards with 5, 10, 25 or 50 dollar values. Players can use this virtual cash to buy items for their characters in games that support a "Cash Shop." The NEXON Cash system has appeared in other games to generate additional funds for their company and keep their games free to play.