Making users logged in permanently

Hi Team,

I would like my users to be logged in permanently automatically. Especially on mobile, i do not want them to be logged out ever. The background is that we are building a mobile app that uses the mobile website version of our Easysocial installation.

For this, I already activated the "remember me" setting automatically for all users. It works great most of the time.
However, it seems that after a couple of weeks users still get logged out occasionally.

Therefore my questions:

1. Is there anything that would log out a user whose session is a "remember me = yes" session?
2. How long does a remember me session hold normally?
3. What do i need to do in order to avoid that my users are ever logged out - unless they do so themselves - ?

Thanks!