I just installed pro version and activate it and after that my website is blank (I see only menu).
I also enabled debug but I do not see any errors 🙁
Also I installed it on another test-website and I get this error:
Fatal error: Cannot redeclare _recaptcha_qsencode() (previously declared in /home2/mrmiller/public_html/duplikat/wp-content/plugins/wp-user-frontend-pro/lib/recaptchalib.php:47) in /home2/mrmiller/public_html/duplikat/wp-content/themes/Creativity/gavern/classes/class.recaptchalib.php on line 55
Seems like your theme is loading the recpatcha library although the User Frontend plugin has this library too.
The library is added to the plugin is such a way that if only it doesn't find a recaptcha library previously, it loads it. Your theme didn't check like this and added directly, thats a fatal error. Remove recaptcha from your theme and it should work.
BTW, I am not seeing any purchase linked to your account. Have you bought the plugin yet?