If you want to cancel your KAYA PRO subscription before your next billing date so you are not charged again, see "How do I cancel or manage my KAYA PRO subscription".
If you have already been charged and want a refund:
iOS: Refunds for iOS purchases are handled directly by Apple. Request a refund through Apple's support page.
Android: Since your subscription was purchased through the Google Play Store, the quickest first step is to request a refund directly through Google Play, since they are often able to process refunds immediately. If you do not hear back from Google Play within 48 hours, reach back out to KAYA support and the team will be happy to help issue the refund. When you do, include the email address associated with your KAYA account and your KAYA username.