The Subscription Started event is only available for Subscription Automation. This event will trigger when a new subscription is created. If you are selling a subscription with or without a free trial, this event will trigger at the time of purchase. This event is used most commonly by companies that are selling the same subscriptions across multiple checkouts, so they don’t need to setup integration actions on each individual checkout, but can set them up here at the Subscription level to grant access and run other necessary actions when the subscription is purchased.