If a purchase was accidentally made on your Android device by a friend or family member using your account, you can request a refund by following this link: https://support.google.com/googleplay/workflow/9813244

If you discover a Google Play purchase made with your card or other payment method that you didn't authorize and that wasn't made by anyone you know, report unauthorized charges within 120 days of the transaction by following the link: https://support.google.com/googleplay/answer/2851610?sjid=7478795453529829610-EU