Hello Victoria Sean,
Yes, our Popup plugin is mobile friendly. You can see it for yourself – click on Mobile friendly feature here: http://supsystic.com/plugins/popup-plugin/ or look at this screenshot: http://screencast.com/t/Q6PYexLJ.
No, you don’t need buy pro-version. Our popups looks good irrespective of versions. With pro-Popup you will have more features and opportunities.