"How many times have you downloaded an app that could supposedly solve all of your computer problems absolutely free of cost? Now ask yourself how many times that app actually did what it was supposed to, or better yet how many times that app was actually free? More often than not your answer is going to be zero.
Unfortunately for all of us, most software providers use gimmicks to sucker consumers in to purchasing their enterprise security apps: Sure, they'll keep your computer virus free for 30 days, but after that you'll need a subscription. Otherwise they'll just scan your registry for bugs but won't fix them for you. Frankly, we're tired of that."