Bought, downloaded and installed online - so would it work if my PC operating system (Vista) would have been here up to date. After registering stopped the installation of anti-virus software because important operating system updates were missing - actually a good feature. Because the fixes required to restart the PC, I had to start over. However, this was not possible because by reading the registry at the beginning of the first installation of the license key was used. Also with the help of e-mail address and password, which are filed with the Registry in, another download was not possible. I then purchased ESET Smart Security. The registration only occurs after installation, as with most other programs as well. Therefore only 3 stars