Thema: Permissions

I'm having a slight problem with permissions. I've bought two different membership systems for Joomla (RSMemberships & Account Expiration Control) and regardless - when someone gets a membership and has their account group changed - they still have to log out and back in again to see any changes on site.
Is there a way I can make Joomla force the permissions to refresh automatically without having to force the user to logout and back in?

please ask where you bought the membership systems.
And please... this is a german forum ;-)