User is refer to the developer who will be editing the maps. If you are
the only person who will be using the software to create/edit maps, that's
refer to as a single user. You can also select a TWIN license (an option
available on the checkout page), or the SITE license option if you have
more than 3 users.
Domain is refer to the websites where the map will be hosted. For example,
if you use the maps on
www.pwc.com, uk.pwc.com, it is count as just 1
domain name (as both belongs to the same company, pwc.com).