How are licenses assigned to users?

Licenses are automatically assigned to invited users. The first goes to the user who installed the application. Each time this individual shares contacts with a new user, another license is allocated. When sharing with a domain group, each user in this group requires one license. 
If the number of users exceeds your available licenses, the additional users will be marked as “Unlicensed.” You can remove a user to transfer their license to someone else.