If one of your users logged out, don't worry!
There are easy ways to log in again. If they exit the app, they can enter the company code on their mobile devices, which can be provided by you. You can find it in your Launch Pad.
If any of your users deleted the app, they can use this links to download it again and then enter your company code.
Link for iOS devices: https://appsto.re/il/yHN2cb.i
Link for Android devices: https://play.google.com/store/apps/details?id=com.connecteamco.Connecteam.app
One link for both devices: https://bit.ly/Connecteam