Why even though I select the “Next time automatically sign me in” option when signing in to Community Server after a day I have to log in back again?

For quite some time I've been wondering why even though I select the "Next time automatically sign me in" option when signing
in to Community Server I still have to log back in the next day. I am suspecting it has something to do with cookies but I haven't had time to look into it. Any ideas?