Sessions in Vevox are controlled by the Session Status. This is the place where you start your session and end your session.
The session status will appear in the drop-down menu of the Session information panel of your dashboard.
A session can either be;
Started: The session is active and available for participants to join.
Waiting: The session is ready to begin, participants can join the session but cannot access the messaging or polling.
Stopped: The session is inactive and cannot be found by participants.
When you first create a new session it will always begin in the waiting state.
To start a session:
When opening the session card, a warning message will appear at the top, asking you to start your session. Press the 'Start session' option. 
Alternatively use the session information panel drop-down and select the 'Start session' option. 
If you attempt to start a session whilst you already have one running you will be warned that by continuing to start this session will result in the other active session being put into a waiting state.
Any participants that are connected to a session will be disconnected when the session is stopped.
To end a session:
From the sessions list (click on the Vevox logo top left corner) choose the relevant session card.
Go to the session information panel in the middle top of your screen and press the drop-down arrow.
From the drop-down menu, select the 'End session' button. Your session will now be stopped.
How long can my session stay open?
Your session can stay open for as long as you wish, or until you start a new session and put it in 'started mode', in which case the current session will go move into the waiting state.
Troubleshooting
If you are trying to start a new session, but it won't start and stays in 'waiting mode', try refreshing your page.