Extended security updates are available. This can be activated for free using Microsoft Activation Scripts.

Microsoft tech support has been repeatedly caught using these scripts to resolve support tickets for license issues. (bleepingcomputer.com/…/microsoft-support-cracks-w…) Also, the open source MAS code is hosted on Microsoft-owned Github, so they are appearantly not very concerned with people taking advantage of this exploit.

If you go this route, please also see the FAQ entry here. There is currently a glitch with commercial ESU keys (which this uses) and Windows Update will continue to claim that your device will no longer receive security updates. This is also effecting W10 LTSC systems. However, you can verify that the license key is active through Command Prompt and instructions are given in the FAQ.