Microsoft has said that certain anti-virus products will not receive its bundle of January 2018 security patches (including mitigations against the Spectre and Meltdown CPU flaws) unless their products certify that they dont make unsupported calls into Windows kernel memory. Microsoft is demanding that the products certify their software work with its fixes by adding a registry key every time they startup. The last thing they want to do is roll out an update that causes computers to crash, so theyre probably right not to push out security updates to that PC.”]
Source: https://grahamcluley.com/anti-virus-registry-key-windows-security-updates/