Yes, you can run the Floating License Server and USB FLEXid keylock on a virtual machine as long as the virtual machine's MAC address does not change.
When the Floating License Server and USB FLEXid keylock is setup on a virtual machine and you need to move to a different physical machine, the license file will have to be re-hosted. This is because moving to a different physical machine will change the Ethernet address of virtual machine, which will invalidate the license file.