How can I enable multi-user remote desktop on a non-server Windows system using mimikatz?

You can use the mimikatz tool with the commands `privilege::debug` then `ts::multirdp` to enable multi-user login by modifying the termsrv.dll in memory. This allows different accounts to log in simultaneously, but the change is lost after reboot. For more context, see the original article on Penetration Techniques - Multi-user Login for Windows Remote Desktop.