The Siemens 6ES7823-1FA00-0YA5 is the SIMATIC S7-PLCSIM Advanced V1.0 SP1 Floating License. It is an option for simulating S7-1500 & ET200SP controllers, allowing for virtual commissioning and testing. The software and documentation come on a DVD, with the license key on a USB stick. It supports Windows 7 (64-bit) and Windows 10 (64-bit).  this product has been discontinued since October 1, 2021, and its successor is 6ES7823-1FA01-0YA5. If you're looking for the latest version, you might want to check that out!