It's not quite a mining pool. You don't solve shares and get it back tied to that share.

You sell computing power for $x/hr, and you get paid $x-%/hr, as two completely unlinked things.

As others have pointed out, it's not a pool. They're a service for connecting people with miners to people who want to mine something. They're a hash reseller. A user bids for mining power and where they want it assigned. Miners post rates they're willing to mine at.