I have an idea
Make a autorun file (just google that to find out how it's done)
Then create a setting called "lockdown" and save it as string with the default value of "".
Add this code to the loading event of your first form (probably Form1)
Is this what you were looking for?
If My.Settings.lockdown = "" then
My.Settings.lockdown = My.Computer.Name
'Checks if the variable is the same as the computer name
'The (Not) is there for inverting the result, so if this=> My.Settings.lockdown = My.Computer.Name is true, it will act as if it's false and the other way around.
If Not(My.Settings.lockdown = My.Computer.Name) Then
'Exits the application if the (lockdown) setting and the computer name aren't the same