There is no keeper. The wallet whose trade triggers the pour is the runner and receives twenty five basis points of the pot in the pair asset, paid in the same transaction. A busy coin pours on the minute because somebody is always trading. A quiet coin pours when the next person shows up, with everything that accumulated in the meantime.
The coin page tells you when a pour is due, and the trade panel says so above the button. If you want the runner's fee, trade when the countdown reads zero.