Board Thread:General Discussion/@comment-68.52.64.12-20160831035727/@comment-27904998-20161002051328

You just need to be connected to the internet to be online. Now in addition to that, if you connect to Facebook through the game and give it permission to access your Facebook account, then your progress will be backed up.

I never log out of Facebook. When I'm done playing, I close the app. When I open the app again, it logs in and I continue. Have a look at the help for your device to see how to close an application.