If you come across this message when you login to Goodnotes Android, Windows, and Web and are unable to access paid features, it is likely that you have already used this account for a one-time payment on the Apple App Store.
Please note that the One-time payment option provides access to premium features exclusively on Apple devices and does not grant access to the paid features on Goodnotes for Android, Windows, and the Web. However, you can continue to enjoy the free version of the app. To find out more about Which subscription is best for me.
If you would like to enjoy paid features on iOS, Android, Windows and Web, but have already made one-time purchase on iOS, you can request a refund through Apple Support for your one-time payment. Please be aware that Apple has full discretion in granting refunds. Once the refund is granted, you can then subscribe annually to Goodnotes 6 through the iOS app. Alternatively, you can subscribe to Goodnotes Pro through Goodnotes for Android, Windows, and Web.
Please note that library sync between iOS and Android, Windows and Web is not supported at the moment, even on paid version. Learn more on how to share documents across platforms.