The hosted domains feature of a hosting account denotes the number of registered domain names that one can add within the same account. Registering a domain and hosting it are 2 totally different services although a lot of people consider them to be the very same thing. While the registration means that you become the owner of a certain domain, the hosting aspect is what in fact allows you to have a site considering that this is where your data and e-mails are going to be. Since these are two independent services, you'll be able to register a new domain with one company and host it with another one by changing its name servers (DNS) - the domain address will work in the exact same way just as if it was registered and hosted using the same company. It is also important to know that changing the hosting means pointing the domain address to a different company and not transferring it.