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 Windows 10, go to: Start > All Apps > GenArtsSapphire AE > Check for Sapphire AE Updates.
On Mac, go to: /Applications/GenArtsSapphireAE/Check for Sapphire AE Updates.

You can also go to http://www.genarts.com/support/downloads/sapphire/after-effects.