Many OEM manufacturers provide trial versions of anti-virus programs preinstalle
d on computers as part of their software package. It is not uncommon for a computer manufacturer to partner or enter into an agreement with a well known anti-virus vendor to include their product as part of a marketing strategy for generating revenue
. Computer advertisements that say they include anti-virus protection is a selling point for many buyers. When the trial period expires, the user will have to either remove the software or purchase the full version in order to keep using the anti-virus software. Since most folks know very little about computer security and anti-virus software, many tend to keep whatever came with their system when they first purchased it. Thus, the anti-virus vendor recaps the cost of providing the trial version for free.
As a preinstalled product...this also means the anti-virus software most likely will be included on your factory recovery disks. If you ever reformat using the vendor's recovery disks, the anti-virus will be reinstalled as part of the default software that came with your computer.
Although McAfee is as good as any other well known anti-virus program, it requires numerous services and running processes that consume a lot of system resources and often results in complaints of high CPU usage. Anti-virus software components insert themselves deep into the operating systems core where they install kernel mode drivers
that load at boot-up and create files/folders/registry entries in various locations. If you do a Google Search
you will find there have been numerous complaints about it affecting system performance.
Further McAfee products, like Symantec, are becoming difficult to remove and remnants are often left behind which require the use of a special removal tool, otherwise you may encounter problems installing a replacement anti-virus. To be fair, other vendors are also using removal tools for the same reason. Those issues plus the cost factor are the primary reason many folks look for a free alternative. IMO, McAfee is better utilized in an Enterprise system environment
protecting many client computers.