How do I get a refund for the Premium subscription?

1. Log in on Apple's website
2. Click "I'd like to".
3. Select "Request a refund".
4. Choose a reason and click "Next".
5. Select "Converter".

Apple reviews the request within 48 hours and has the right to deny it.

The subscription is set up through the App Store, so a refund can only be requested there.