Plans have an optional trial period that may be specified in days or months. The paid subscription will begin at the end of the trial period.
When Recurly processes a new subscription request, it will attempt to charge the full subscription's billing period price for subscriptions without a trial. If the subscription has a trial, Recurly will attempt to validate the credit card using a $1.00 authorization (and will immediately void the transaction). If the subscription is canceled any time before the end of the trial, the account will not be charged and the subscription will expire at the end of the trial. Otherwise, the subscription will be billed normally at the end of the trial.
Please note that adding a free trial to a plan will extend the subscription term depending on the length of the trial. For example, an annual plan billed monthly with a 30 day free trial = 13 month long subscription term.