Any unused portion of a free trial period, if offered, will be forfeited when the user purchases a subscription to that publication, where applicable.
You can cancel a free trial or subscription anytime by turning off auto-renewal through your iTunes account settings.
This must be done 24 hours before the end of a free trial or subscription period to avoid being charged.
The cancellation will take effect the day after the last day of the current subscription period, and you will be downgraded to the free service.
Account will be charged for renewal within 24-hours prior to the end of the current period, and identify the cost of the renewal.