Restore Previous Purchase only occurs when you purchase the free version, PDF Reader Pro - Lite Edition, from Apple Mac App Store. You don't need to enter license code.
Restore Previous Purchase directly in the upgrade window and do not need to re-pay. If it shows Restore Success, congratulations, the previously locked functions (add/remove watermarks, etc.) have been activated and can be used normally. If it failed, please contact us: firstname.lastname@example.org and provide your purchase record.
Due to Apple needs to confirm your purchase info, you may be required to sign in with your Apple ID. When you restore your purchase, make sure you use the same Apple ID previously used to purchase the app.
If you install different versions of PDF Reader Pro on your computer, please uninstall all PDF Reader Pro on your computer and then download and install it again from the Mac AppStore.