You need one license per machine that is running the software, or has the software installed at the same time. You can uninstall the software and move it between machines.
Example 1: You run a company which tests machines and wish to test each new machine as it arrives, one machine at a time. After testing, the software is removed. In this case, one license is required.
Example 2: You want to have the software permanently installed on ten machines. In this situation, ten licenses are required.
Example 3: You have five staff in the field repairing and testing PCs, and each technician carries a copy of PerformanceTest with them on a USB drive. Here, five licenses are required assuming the software is always run from the USB drive.
Coverage for an unlimited number of machines and users within a single organization within a single country. It is possible to purchase multiple site licenses for multiple countries