How to Lock your Windows PC or Laptop with USB

• In order to use lock your computer you need to get a software tool "Predator"Professional Edition here[official link] and Free Edition from Here[official link]
  Choose the best suitable one depending on your operating system bit.
• After Downloading after Predator. Connect the USB Drive that you want to use as key to your computer.
• And then run the predator installation.

• Before continuing installation. A popup will ask you to create the new password, Enter your desired password and then hit on Ok to continue.

• Now predator will present you a box with preference settings.

• You can change settings as per your need and you can add the USB drive by selecting the drive under Flash Drive settings and hit on create key to generate a key on the usb which will be used by the predator to monitor.

• When Predator is running on your computer you can see the predator icon in the taskbar as shown in below image.

And Predator offers one month free trail of the Professional edition which include sending of twitter messages to you and many more features.