Could you please confirm that this does not come into play. (My assumption is that clients do not use the database, the database is about the clients.)
Multiplexing: Using Middleware, Transaction Servers, and Multitiered Architecture
Sometimes organizations develop network scenarios that use various forms of hardware and/or software that reduce the number of devices or users that directly access or use the software on a particular server, often called "multiplexing" or "pooling" hardware or software. Use of such multiplexing or pooling hardware and/or software does not reduce the number of client access licenses (CALs) required to access or use SQL Server software. A CAL is required for each distinct device or user to the multiplexing or pooling software or hardware front end. This remains true no matter how many tiers of hardware or software exist between the server running SQL Server and the client devices that ultimately use its data, services, or functionality. An exception to this includes the manual transfer of data from employee to employee. For example, if an employee sends a Microsoft Excel version of a report to another employee, the receiving employee does not require a CAL. An additional exception is communication exclusively between the servers running SQL Server.