Although it is not a big money, to be careful of your subscription cancellation as no one like their money be stolen. First, check if there is a confirmation letter for cancellation to your mailbox. Keep it. It can be used as evidence when there is unauthorized charging in the future. Second, is it weird that you cannot remove your card information from the website? If you cannot remove it, the bank will always pay if match think you still have a subscription.
I have been suffered 2 times strange charging from this website, and is my reminder to you.