If you have an old BirdieSync 2.x license or a BirdieSync 3.x license older than one year, you can upgrade on BirdieSync web site with your previous registration key.

But the simplest solution, is to do it directly from BirdieSync application:

• Open BirdieSync main window (double click on BirdieSync green icon in Windows task bar)
• Open BirdieSync menu "Help/License..."
• Click on "Upgrade your license..." hyperlink

Your previous license will be directly uploaded and you'll be able to benefit from the upgrade price.