I was really disappointed with MalwareBytes. It seemed great, so I paid for it, and every other week it would de-activate itself without warning. I would only notice this when explicitly checking the control panel, to find it had been turned off, and I needed to re-enter the license key.

Maybe they've improved it? I should give it another shot!

I use the paid version personally, but not many people are willing to spend the $70 on it.