Rated 4 out of 5 stars

UPDATE: It appears that it was not this add-on that was causing my problem. I've changed my rating to the current average rating of 4 stars.<br>

Severely broken (1.16.1). Even after being removed from Firefox, this add-on made it so that *none* of my logged in sessions were remembered after restarting Firefox. Every website was logged out of when Firefox was closed. I had to delete several of the add-on's entries in about:config to be able to remain logged in anywhere across Firefox sessions.

This review is for a previous version of the add-on (1.16.1). 

This extension is incapable of doing that you described. Either you disabled auto login in Firefox itself, or installed another addon that did it for you (LastPass perhaps?)
Now, I'd like to see these "several add-on's entries" you are referring to, because the settings this addon uses are useless if you uninstalled this addon. No other setting are changed by this addon.