For many, Google Earth Pro is an excellent tool and resource in real estate and is available at no charge via download. Based on information obtained from Google, you can use imagery from Google Earth Pro as long as you retain the Google copyright on those images. Since it became a free product, there are no additional permissions required.
In order to download the software, you will need to accept the Terms of Service and use the license key code along with your email address.
For technical support with this product, please refer to the Google Earth Pro support site. There is where you can file a ticket regarding a particular technical need related to this software.