The payment is charged to your account after a confirmation of purchase The subscription is renewed automatically unless you turn it off 24 hours before the end of the current period.
Any unused portion of a free trial period, if offered, will be forfeited when the user purchases a subscription to that publication, where applicable.
Account will be charged for renewal within 24-hours prior to the end of the current period, and identify the cost of the renewal.
If you want to cancel a subscription during its free trial, you have to cancel it through your account in the Store.
This must be done at least 24 hours before the end of the free trial period to avoid being charged.