Turn it on
Publish a flow with the Live toggle. It appears in the flow editor header, in both the Steps and Canvas views, and on the flow's card on the Automations page, where a live flow shows as Active.
Before it can go live
The flow must be complete. On the canvas, every required output must be wired, or the toggle stays disabled with "Wire N handle(s) to go live". In the Steps view, all fields must be valid, or you will see "Fix the highlighted fields to save". Activating a Workflow is available on the Business plan.
Versions and live runs
Each time you publish, the flow gets a new version. Publishing also ends any conversations that were part-way through the old version, so those customers restart on the new one at their next message.
Turn it off
Flip the same toggle to turn a flow off. It stops running immediately, and your draft stays saved in your browser so you can edit and republish it later.