Purchase Export Calendars Pro
It is currently not possible to purchase directly from the developer. Just purchase the app from the Mac App Store.
If the Mac App Store is not an option, don't hesitate to send me a support request using the corresponding function in the app's Help menu to discuss other ways to obtain a license.
Notify the developer
Feel free to let the developer know anonymously that you need a version that is available for purchase outside of the Mac App Store.
Download on the Mac App Store
Easy update process, no license key required, payment via Apple.
Please delete any downloaded demo versions of Export Calendars Pro from your Mac before downloading the app from the Mac App Store. Sometimes the Mac App Store gets confused because it thinks the app is already installed and then the installation fails.