Your payment will be charged to your iTunes Account once you confirm your purchase.
Your iTunes Account will be charged again when your subscription automatically renews at the end of your current subscription period unless auto-renew is turned off at least 24 hours prior to end of the current period.
You can manage or turn off auto-renew in your Apple ID Account Settings any time after purchase.
No cancellation of the current subscription is allowed during active subscription period.
Any unused portion of a free trial period, if offered, will be forfeited when the user purchases a subscription to that feature, where applicable.