Hello Rod,
Yes, you can choose that popup will show one time.
If you want that popup will show for all visitors or just for first-time visitors or show popup in some pages, but just once – choose at the Main tab setting: http://screencast.com/t/bhQnbz0B2O
More about this you can read here: http://supsystic.com/until-user-makes-an-action-subscribe-share-like/ and here: http://supsystic.com/for-first-time-visitors/
If you still have questions – feel free to ask.
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