We are setting up a new site. Initially, this will be on a "staging" host, then we'll move it to a permanent host. While on the staging host, we will need support. Once we move it, we'll need to have support on the production site - will we be able to add the new domain or will we need to switch? This is purely from a support standpoint.
Your licence covers support for 1 domain but if you setup your site on mytestsite.com then move it to the live environment
www.thenewsite.com
then we will happily change the supported domain as long as it is the same site. The only time changing domains for support is a problem is if it is a different site.