Named User means "Non-Concurrent User" or "User Seat" within one organization/company/firm. A "Named User" is one person/user/author with access rights to edit-on Pro in any form. All "Named User" may use edit-on Pro concurrently (= simultaneously) or non-concurrently (= non-simultaneously). The Seat License is NOT  a 'floating' license, that is, you cannot temporarily transfer access rights to another user. When your user base grows to the point that you have the 11th, 21st etc. unique Named User, you need to purchase additional Seat License Packs (10 Named User)  to cover the new user seats.

IMPORTANT: edit-on Pro Seat Licenses are for 10 named users, not 10 concurrent users!

Simply said: If you have 10 different people within an organisation who work with edit-on Pro, this means you need an edit-on Pro Seat License with 10 named users. If you have 50 different people within an organisation who work with edit-on Pro, this means you need an edit-on Pro Seat Licnese with 50 named users.