MICROSOFT IS PUSHING its Windows Defender Advanced Threat Protection (ATP) subscription service into Windows 8.1 and Windows 7 for people too lazy or mad to upgrade to Windows 10.
The enterprise security service has previously been exclusive to Windows 10, presumably because Microsoft wants to encourage users to upgrade to the latest version of Windows. Given the boosted functionality and fresh but familiar user interface of Windows 10, we’d also expect people to make the upgrade.
The Inquirer
Windows Defender is not a great AV but better than nothing.