Why do I get “Endpoint Protector Basic is expired.” or “License key is incorrect.” messages on macOS 10.13 (High Sierra)? (Discontinued)

This thread is linked to a previous FAQ relating to Kernel Extensions (KEXT). The issue can be eliminated by following the simple steps described here.

Due to Apple’s policy regarding third-party KEXT, the system extensions signed by CoSoSys need to be approved during the Endpoint Protector Basic installation.
If not, some of the processes needed by Endpoint Protector Basic may not function properly, leading to messages referencing expiry, incorrect or invalid licenses.
Approving CoSoSys KEXT is a onetime process. If this has already been done in the past, it will no longer be required for any new installations of the product.