Source of Truth is licensed on a per-machine basis.  When an expression of interest is received by FFP Software, an account is created in the FFP tenant in Azure and a unique account number is issued.  This account number is used by the SoT update mechanism on the local SoT server to contact the FFP licensing system and retrieve the customer licensing record. 

The number of records in the local SoT database is compared to the number of licenses purchased.  If the local database has more records than the number of licenses purchased, then the database will stop accepting connections and data updates from the endpoint machines.  The SoT web page on the SoT server will also change to red and have (UNLICENSED) after the title.  Likewise, if the subscription date lapses, the same occurs.

In the event of license numbers being exceeded or the subscription lapsing, contact FFP Software to purchase more licenses or extend the subscription.

The licensing mechanism on the local SoT server reaches out to the FFP licensing system multiple times per day (the data involved is only several KB) to ensure license compliance.  This is logged to a folder in C:\ProgramData and a maximum of 100 logs are kept