Joomla! 3.5.0 and php7

Tuan Pham Ngoc wrote: There is some changes in Joomla 3.5.0 causing the select user option when creating new registration in the backend doesn't work. I just updated download package with the fix. So if you update your site to Joomla 3.5.0 (there are still some issues with Joomla 3.5.0, so you should wait until 3.5.1 release before upgrading), please update your site to latest version of Events Booking

And Events Booking works well with PHP 7, too. PHP7 is much faster compare to older version of PHP, so if you upgrade your site to Joomla 3.5 and have all extensions compatible with PHP 7, you should use PHP7 for your site