Proximity Lock
Hideez Key — Proximity Lock
To lock your PC, you can:

Lock your PC by proximity

You can read about the proximity mechanism and its limitations here.
The step-by-step algorithm for configuring PC lock by proximity is described here.

Forced methods to lock your PC

Method 1
Press the Win + L key combination on the keyboard. The PC will be locked. Method 2
Unpair key in Windows Bluetooth devices.