I paid for it...
but only recommend the free one to my clients, because it's true use is the crazy fast boost scan. It can make quick work of even a terabyte drive in boost mode! When I go on a rescue mission, it always finds even more malware, even after scans from many reputable brand names. The last time I used it in safemode, it made serious hay of many hidden malware variants - but a ZAccess backdoor new the jig was up, and blocked any subsequent boots. It was a zero day threat, and even Kaspersky's Rescue CD 10 couldn't get rid of it. Two days later, Avast was able to remove it from the backup folder.
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