The hosted domains feature of a hosting account indicates the number of registered domains that one can include in the same account. Registering a domain and hosting it are two completely different services although some people consider them to be the same thing. While the registration ensures that you become the owner of a certain domain address, the hosting part is what actually permits you to have a site since this is where your data and e-mails will be. As these are two independent services, you are able to register a new domain with one company and host it with another one by modifying its name servers (DNS) - the domain is going to work in the exact same way as if it was registered and hosted using the same company. Additionally, it is very important to know that changing the hosting means directing the domain address to a different company and not transferring it.