Display Condition: Show up to X times
If you want to offer a promotion to a limited number of people then you can do that with HollerBox.
Editing your popup, then you want to show the Display Conditions.
When you can edit the display conditions, you will want to turn on Show up to X times, then you can input the number of times you want this popup to show.
You then can close the editing of display conditions (top-right corner) and then save/publish your popup.