Is Google Earth Pro free

No, google Earth Pro is the paid professional version that costs $399 per year.

It does have a free 7-day trial period to use and evaluate after which you need to convert trial license into full license.

Note that Pro and free version both use the same high-resolution imagery.

*UPDATE* as of Jan 30, 2015 google made google Earth Pro available for free. Login with your email address and the license key GEPFREE and that's it.