BaseElements is available in two licence types, Single User and Site Licence.
Both licences allow you to run BaseElements as either a Runtime or FileMaker files 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 Site Licence also allows you to run BaseElements on every computer at a company or all computers used by employees of that company. As well as that you can run BE on FileMaker Server and access it by other machines in the same company.