Autodesk Simulation software (CFD,Moldflow etc.) which has local solver service installed, would be requesting the license as a System account.
If you need to control license usage on username you could change login user for the simulation service and then creation the license option file accordingly.
In order to change the username please follow the steps below.
Start ->Run/Search->Type services.msc->click OK.
Double Click the service related the simulation
Click on Log on.
Choose This Account
Type your user name and password. Please note you will need to update the password, when you change the logon password.
Thanks David Lau for requesting for this post.