You can cancel a subscription made to any Model, at any time, by logging into your Membershyp account and going to "My subscriptions". 

    There, go to "Active", find the subscription you want to cancel and click on the "Action" button, as you can see in the picture below.


    You will still have the "Active" status for the remaining days of that subscription but this will stop that subscription from being renewed again, so you will not be charged again anymore.