Cancellation fee

Dear Rabbi, I signed up for a physical fitness course. They let you know right away that if you want to cancel your subscription, you have to let them know about it a month in advance. And if you don’t let them know a month ahead of time, they’re going to charge you for the next month. Practically speaking, there is absolutely no need for this requirement. I don’t come at somebody else’s expense! I don’t think any damage is going to be caused I if cancel without telling them. My question is: can I cancel my subscription against their will by cancelling my standing order in the bank? Or do I have to pay for the extra month? Thank you

Dear …

Even if this requirement isn’t justified in any way, if this is what you agreed upon from the beginning, you must pay as per the agreement.