Payment will be charged to iTunes Account at confirmation of purchase.
If the subscription has a free trial, the payment will be charged 24 hours before the end of the subscription, unless the subscription has been cancelled.
Subscription automatically renews unless auto-renew is turned off at least 24 hours before the end of the current period.
Account will be charged for renewal within 24-hours prior to the end of the current period, and identify the cost of the renewal.
Subscriptions may be managed by the user and auto-renewal may be turned off by going to the iTunes Account Setting >Apple ID after purchase
Any unused portion of a free trial period, if offered, will be forfeited when the user purchases a subscription to that publication, where applicable.