The plugin now works seamlessly on its' own without the user credits plugin.

Install it if you are interested in ensuring that the popup does not appear after the user likes your page. This feature is NOT available in 3X FACEBOOK LIKES. 

Please note that this feature only works for registered users that are logged in at the time when the popup is shown. Unregistered users will still see the popup after they like your page. You can control how often the popup shows for unregistered users by increasing the cookie delay in plugin settings.