If you're looking for a refund on a Noteflight Learn or monthly/annual Premium subscription, you can request one 30 days after signing up/renewing to get your money back. Noteflight Premium Lifetime subscriptions cannot be refunded. Here's how to request a refund:
Log in to Noteflight and click on your Profile picture in the upper right corner, then click "Account." 
From the Account page, choose "Subscription" in the left-hand menu. 
Under "Plan", you will see a link saying "Contact Sales for Refund". 
You can then email sales requesting a refund and you will receive an email back confirming your cancellation and the amount will be refunded to your credit card within 3 days. If you have any problems with this process, please email support@noteflight.com.