The Per Server licensing mode is a new option that has been added for Microsoft Windows NT Server 3.51 or later, Microsoft SNA Server 2.11 or later and, when released, Microsoft Exchange Server 1.0. This option enables users to take advantage of the concurrent connections (Per Server) option that has been available for Microsoft SQL Server 4.21a or later. It is not available for Microsoft Systems Management Server or the Microsoft BackOffice Client Access License.
If you are ever unsure, though, about which licensing mode to choose, select the Per Server option. If your network traffic later increases and more users need to connect at the same time, you are legally permitted to convert from Per Server mode to Per Seat mode at no additional cost. (Use the Licensing option in Control Panel for a server on which you are working and License Manager in the Network Administration program group for local or remote servers.) This is a one-time, one-way conversion option.
It is not necessary for you to notify Microsoft if you elect to make this change. However, you will need to reenter the licensing data in License Manager using the New Client Access License dialog box. You are not legally permitted to change the licensing mode from Per Seat to Per Server.
Note
If you purchased Client Access Licenses for Windows NT Server 3.5 (which were in Per Seat mode because that was the only licensing mode available with Windows NT Server 3.5) and now want to use them with Windows NT Server 3.51 in the Per Server mode, you can designate them as Per Server mode when you upgrade (but not later). Normally, converting from the Per Seat mode to the Per Server mode is not allowed. However, since the Per Server mode is new, Microsoft is allowing customers that upgrade to Windows NT Server 3.51 to choose the most appropriate licensing mode for their requirements.