The Genesis Framework and Genesis child themes, like WordPress, are released under the terms of the General Public License (GPL). What this means, in layman’s terms, is that anyone has the freedom to use WordPress however they like. Included in this license are the rights to use WordPress and any other themes and software released under the GP License with as many commercial projects as you like, without needing to pay extra licensing fees.
Intelligent Web has a support contract with StudioPress that helps us support our clients and which gives us the rights, under the GPL license, to install both the Genesis Framework, and any other StudioPress themes on as many of our client websites as we like.
Clients have an option to purchase a support contract from the theme developer, StudioPress. This support contract will include a licensed copy of both the Genesis Framework and a child theme with the design package chosen. StudioPress provides unlimited theme support and updates for the selected theme.
Quote from the StudioPress site
A framework (ours is called Genesis) is a powerful type of WordPress theme — the frame and body of the car — that acts as a design, security, and SEO foundation for your website. It also “future-proofs” your site customizations, so there’s no hassle when it comes time to upgrade your software with one click.