I have often found the SQL Server licensing models to be plagued by confusion and very poorly understood. Recent changes in processor technology, including the introduction of hyperthreading and multicore technologies, have further complicated matters. This section attempts to explain the licensing considerations for SQL Server 2005 deployments in simple terms.
SQL Server 2005 can be deployed using one of three distinct licensing models:
Server plus user client access licensing. Requires a license for the system running SQL Server 2005 and a client access license (CAL) for each user that connects to the SQL Server instance.
Server plus device client access licensing. Requires a license for the system running ...