Google has announced the subscription fee for Google Earth Pro has been eliminated, making this software completely free.  It still requires a license key, which is provided on the download page.

System requirements:

PC – Windows XP, Windows Vista, or Windows 7

Mac – Mac OS X 10.6.0 or later

Features of Earth Pro:

View demographic, parcel and traffic data layers

Use advanced GIS data importing features to your advantage

Measure area, radius and circumference on the ground

Print high-resolution screenshots

Make compelling offline movies to share