Pro: schedule
In Schedule choose From and To (date and time of the site, in Settings > General) and, if you want, Only on these days. Empty means always.
When the end has passed the popup is marked Schedule ended and leaves the pages. Without the licence a scheduled popup is paused, so that a Christmas offer never appears in March; the screen of the popup has a button to remove the schedule.
Still stuck?
webadmin@nopvideo.comWrite to us and tell us which plugin, what you tried and what you see. We answer from Italy, usually within one working day.