I can't remember when I last scanned for rootkits. ...GMER, Malwarebytes, etc... https://www.bleepingcomputer.com/download/malwarebytes-anti-rootkit/
Can you give some examples of memory rootkits? And perhaps it should also be mentioned that kernel rootkits can't actually modify the kernel on Windows 64 bit systems anymore, so they are less aggressive then back in the days. But of course malware like SmartService can still be a pain.