Workspace owners and admins can set up session duration for the Slack desktop app and browser. With session duration turned on, members won't be signed out of their Slack mobile apps.

1. From your desktop, click on your workspace name at the top left.
   
2. Select Settings & administration from the menu, then click Workspace settings.
3. Click on Authentication.
4. Next to Session duration, click Expand.
5. Choose if you’d like to sign members out whenever they close Slack or after a set period of time.
6. Click on Save.

Note: Changes to session duration will take effect the next time that a member ends their current session and signs back in to Slack.

Org owners and admins can set up session duration for the Slack desktop and mobile apps.

1. From your desktop, click on your workspace name at the top left.
   
2. Select Settings & administration from the menu, then click on Organisation settings.
3. Click  Security in the left column, then select Security settings.
4. Next to Session duration, click Enable.
5. Tick the box next to Sign users out on desktop or Sign users out on mobile.
6. Choose if you’d like to sign members out whenever they close Slack or after a set period of time
7. If you like, choose to Notify users when they need to log back in. 
8. Click on Save.

Note: Changes to session duration will take effect immediately and be applied to members’ sessions over the timeframe that you’ve selected.