This is just a free subdomain service using a cleverly registered domain. They have no official relationship with .us nor is it a real TLD. At any point in the

This is just a free subdomain service using a cleverly registered domain. They have no official relationship with .us nor is it a real TLD. At any point in the future they could demand money to renew or just point your domain to a page full of ads. Very similar to things like us.com or eu.org.