BaseElements is available in three licence types, Single User, Multi User and Company Licence.
All licences allow you to run BaseElements on a single machine at a time. You can also put the FileMaker files on FileMaker Server and access them from FMP, although with a Single User licence you can only access the files one user at a time.
The Mutli User Licence also allows up to 5 users to use BaseElements.
The Company Licence allows unlimited users at a single company.