A license key is a code that authorizes the software and contains information about the type of product you purchased, the version you can use, and how long you can use it for, and is only available in combination with the USB lock that comes with the software, so the software will not run without the USB lock. It is provided as a test file, and you only need to reissue and enter this license key if you want to add more options to your product, or increase the number of users in the network version.