The website is a free demo (with a watermark). No payments are taken on the web.
The full version (PRO) can be purchased only inside the iOS app through the App Store; payment is processed by Apple under Apple's terms.
Refunds for App Store purchases are handled by Apple under Apple's policy: reportaproblem.apple.com
You can cancel a subscription in Settings > Apple ID > Subscriptions on your iPhone or iPad; you keep access until the end of the period you already paid for.
If you paid on the website before, e-mail jinhkim623@gmail.com about cancellation or refunds and we will take care of it.