In October I bought a month of premium, my account since lapsed into a free account again (which was as intended, since I only wanted a month) but the premium content is still available to me, even though it is clearly stated that I am a free user. I just wanted to make you aware of this, I am a big fan of the site and the work you guys do here thus it doesn't feel right to me to keep consuming the content when I clearly shouldn't have access to it but if this is not an isolated issue, someone might just feel otherwise, thus I feel this is definitely worth a look into.
I am using the latest version of Chrome and on top of that I have adblock and ghostery (both of which are whitelisting this domain, so I'm not sure if this is a factor at all). Otherwise I'm using Windows 8.1. Not sure if this info is of any help, let me know if you need any more information about my setup in case you deem it to be important to solving this.