Harold's subscription of Eset Nod 32 is up. Should he renew? Leo says that the world has changed and that's why he doesn't take advertisers for antivirus software anymore. If Harold is running Windows 7-10, or running OS X in Mac, then he doesn't need an antivirus. Windows users have Microsoft Defender (formerly Security Essentials) and nobody really writes viruses for OS X, as Apple has a silent malware detector. There's ransomware that he can get bit by still, though. That's an encryption issue though, and Apple has a malware detector to prohibit that.
Viruses also spread faster now and the bottom line is that an antivirus is a second line of defense that doesn't know about a virus until it's too late (like with zero day exploits). Leo says that the best protection is to alter his online behavior. Religiously install all software updates, immediately after they are available. And have a good back up.