Hi. Logging into the game ALWAYS requires to un-check the "Rember Me" checkbox manually, if you don't make use of that feature. There is NO COOKIE or perhaps only NO CHECKBOX STATE set in all major browsers. So still, I have to uncheck the box XY times a day.
I call this behaviour - to have the box always checked - highly questionable, if you think about security.
Edit: I also don't get why the logged-in state varies. Sometimes I have to log-in only once a day, sometimes every one or two hours and sometimes each 15 mins.