Favourite Posts/Most Popular Plugin?

Yes, one single line is required to fix the
https://www.aufzynden.de/post-readers-wp-plugin/
plugin. Donwload it, then edit it, and look, around line 23 for

get_currentuserinfo();
if ($user_level > 8)

remove them and istead put

if ( current_user_can(‘level_9’) )

Then it works great !