How can I cancel my Apple in-app subscription and get a refund?
Subscriptions bought via iTunes (for iPhone, iPad and Apple TV) need to be managed via iTunes.
Emails about your subscription will be entitled Your invoice from Apple.
Refunds for Apple in-app subscriptions: https://support.apple.com/en-gb/HT202039
Visit Apple’s support pages: https://support.apple.com/en-euro/itunes