You can lock a Windows PC by pressing Win+L. This locks the screen displaying the Windows logon screen. Nobody can use your PC unless they enter the correct user password. This also means that anybody can enter into your computer if they know your password. This is where Predator comes in.
Predator is a free utility that allows you to temporarily lock your computer when you have to move away from it by using your USB flash drive as a key.
The first time you run Predator, you need to install the “key” on a pen drive. As long as the pen drive is plugged into the computer, your computer is unlocked. The moment you take out the pen drive your computer gets locked. The keyboard and mouse are disabled and the screen darkens. There is no way to access the PC unless you plug the USB drive back into the computer. Once the flash drive is back in place, the computer unlocks.
Predator also logs all events into a log file so that you can see if anybody unlawfully gained entry into your PC, or exited the program.
The best thing about Predator is, you can lock multiple PCs using a single flash drive.