Well almost most games have a tracking system done by the marketing department. Like to see how many users are online, how many bought GP, how many are using a WLC, everything you do in game - click and object, move around town, sell buy stuff, all these generate events in a tracking tool, and im pretty sure each character/account has a unique id and i don't think is that hard to track some money, as in how have they been made and were the exact amount ended up.
So every little thing you do in a game generates a specific event :)