The software automatically checks for updated versions. If you would like to check manually:

On Windows 7, go to: Start -> All Programs -> GenArts Sapphire AE -> Check for Sapphire AE Updates.
On Windows 8, search for GenArts Sapphire AE -> Check for Sapphire AE Updates.
On Mac, go to: /Applications/GenArtsSapphireAE/Check for Sapphire AE Updates.

Notifications are also made available through standard GenArts communications, (e.g., newsletters or other email communications).