As others have said, antivirus is almost useless on Android because the OS is not like Windows. The only bad thing that can run is a bad app (APK file) that you intentionally install. You're not going to get a virus (like on a PC) by clicking on a link or opening a document or something.) If you install an app from trustworthy sources, like Google Play or Amazon, then you don't have to worry. If you install a malicious APK from an untrustworthy place, then it's not clear that an antivirus app could do much to help you because I don't think those antivirus companies have the resources comb the web testing every APK that is posted.