Need to cancel impulse brain subscription?.

As with any website subscription, your only option is to work with them to cancel and if that is not possible, you would need to dispute the charge with the bank of your issued card and instruct them to block any further charges.

Apple is not involved in any third party subscription. Those are being billed directly to your card. Apple can only manage subscriptions made using an in-app purchase. Just because a developer also has an app, does not mean that the subscription can be cancelled by Apple. Take for example, Netflix, YouTube, Twitter, and Walmart, that all have apps and also allow you to subscribe with them directly to bypass Apple from being able to cancel those subscription.

Thank you and well done for posting this link.

would have been extremely hard to find this direct link to log in via the web.