It's github enterprise: https://enterprise.github.com/features#pricing
[1] https://github.com/blog/978-introducing-github-enterprise
We have companies scaling their GitHub Enterprise instance up to 25,000 users, and we also have a dedicated Enterprise Support team available 24/5 to resolve any technical issues.
I am not your target market, FWIW, but just a curious developer.
We also recognize that having a SaaS solution like GitHub Organizations meets the needs of many companies (over 75,000 at last count), and our announcement of 2FA enhancements today is an indication of our desire to continue that approach.