Payment will be charged to your iTunes Account on confirmation of purchase.
Subscription automatically renews unless auto-renew is turned off at least 48-hours before the end of the current period.
Your account will be charged for renewal within 48-hours prior to the end of the current period. The cost of the renewal will be the same as the cost of your initial transaction.
You can manage your subscriptions and you can turn off auto-renewal by changing your Account Settings after purchase.