I contacted Prevx yesterday with this issue. See below for my message, and the Prevx reply. Hi I downloaded and used Prevx1 for a few days a month back. I had a clean system and I never had to use Prevx1 to remove any malware. I removed Prevx1 from my system to try CyberHawk, but I have since decided to go back to Prevx1. The problem is when I try to install it, it is saying I need to pay as my trial period has expired... Now I understood Prevx1 was free to use providing it didn't find any infections (as was/is my case), so why am I being told I now need to pay to use it again? The Prevx1 reply in its entirety: Hi, It is free to use providing you continue to use the product and do not uninstall. We will look at changing this in the future. Quotes from the Prevx website: We believe that if your PC is never infected then Prevx1 should not cost you a thing. It should be completely free. And so it is. You can use Prevx1 completely free of charge to monitor your PC for infection. It's NOT free for me to use!