Hello,
I see, you are referring to an actual installed template, not something on our site. The message is just a default message that always shows in the backend of the template, it's not related to your membership status.
If it was working before and not now something on your server or installation had to have changed. You will need to disable all third party extensions on your site to see if one is interfering. Also, check with your host to see if they have done any recent updates to the server. If you are getting this on all your sites, that would point to an issue with the server.
Also, you can try patching Vertex to the latest files:
http://www.shape5.com/documentation/Vertex-Framework/Joomla-Specific/How-To-Patch-Vertex-In-Joomla-and-Changelog