The price that appears for OnSong 2020 on the OnSong website is pulled directly from the App Store and will generally show prices for the app in your App Store country. If you are using a VPN to access content as if you were in the United States, you may receive the price in US dollars instead of your local currency. For instance, if you are in Australia, the price would be $46.99 AUD to account for exchange rate differences. If the website cannot access the App Store information for your country, it will appear with an asterisk that indicates, "Prices shown in U.S. dollars and is adjusted for international app stores and exchange rates."
OnSong 2020 can only set one price globally for the app and Apple dictates the price to be charged in other App Stores. This takes into account currency exchange rates and fluctuations in currency.