Subscriptions may be managed by the user and auto-renewal may be turned off by going to the user's Account Settings after purchase .The cancellation will take effect 24-hours after the last day of the current subscription period and you will be downgraded to the free service.
Please note: any unused portion of a free trial period (if offered) will be forfeited when you purchase a premium subscription during the free trial period.
Subscriptions will automatically renew and payment will be charged to your iTunes account unless auto-renew is turned off at least 24 hours prior to the end of the current period.
You can cancel or manage your free trial's auto-renewal in your Account Settings after purchase.
Subscription with a free trial period will automatically renew to a paid subscription.