The internal license is intended for users that plan to develop and deploy an internal application. The internal application is for internal use only, i.e., only employees and contractors of the licensed organization should have access to it. Customers, clients, and other users outside of the organization should not have access to the application; if you require this, the SaaS license would be the more appropriate fit for your needs.
Each license is for use on a single domain. You can buy additional licenses for additional domains. Purchase of an internal license includes two hours of product support. Additional hours can be purchased through the Pricing page. For more detailed information, see the internal license page.