When creating your delivery you can cap the number of leads sent to your buyer/remote system.
You have the flexibility to choose between Monthly, Weekly, Daily, Hourly and Total caps. You also have the option to break these down even further and split them by day.
All caps refresh each respective timeframe, however the total cap will remain as is until you edit it.
Keep in mind that you won't receive any errors or warnings when your delivery cap has been hit, leads will simply no longer been sent until the next timeframe. If you would like to get an email alert you can set this up under Campaigns > Alerts. More about alerts HERE.
I would also suggest keeping an eye on the "Cap" column located on your deliveries screen as it will give you an indication of how far you are through the cap set.
It is also worth noting that 0 in the cap field stands for no limit. This means there is no cap and unlimited leads can be delivered.