On the login page, there is a “remember” checkbox you can check when logging in.
If you clear your browser’s data cache, that could be clearing your login credentials even if you checked the “remember” checkbox. In that case, you will be logged out of the site.
Shy do I have to login every time I play? I only play tactics and for the lAst few weeks I have to always login otherwise I am seen as a guest. ???????