Thank you for letting us know the issue.
It happens when the cookie file on your computer has not bee updated completely. In that case, could you log-out the site, delete caches and cookies data on your current browser, and log-in again? In that way, you can get new cache for your premium membership when you log-in, and you'll be able to check all contents as a premium member.
If this doesn't work well, please leave comment here or send email to