Since the last update, I’m getting advertisement popups from Firefox, and I only use 2 add-ins; Kee and Ad-Block. I know it’s coming from Firefox because the options (clicking the gear icon) gives options regarding Firefox. Here’s a screen shot of an ad: http://tinyurl.com/yboc5t7v
I don’t think there is a guilty of Kee in appearing this ad. I have the same version and none of ads are shown since I updated to last version.
Furthermore you can view the sourcecode of this extension at GitHub and even buiid it yourself and check out for ads once again.
You must be pretty sure you haven’t any spyware/malware/virus in your operating system.
This ad appearance and updating to last version can be just a coinсidance.