McAfee, like many antivirus software developers, now offers its products with multiple licenses. For example, the default option for purchasing McAfee Total Protection 2009 comes with licenses for three different computers. For a few dollars more, additional licenses are available.
Multiple licenses are becoming increasingly popular as families no longer have just one computer in the household. In your case, if you have the three license version of McAfee, you should be able to install a third copy of the software and activate it with no problem. Here are the basic steps.
Installing the McAfee Software
First, you need to get your hands on the software and install it on the third computer. Did you buy the software at a local retailer? If so, then find the original CD and install the software off the disc. If you downloaded the software from McAfee.com, then sign in to your McAfee account and click on the Downloads link where you should find a link to the software for downloading. Another option is to download the free trial version of the software and install it on your third computer (as long as it's the same version that you are licenses to use).
Activating McAfee on Multiple Computers
Once the McAfee software is installed on your third computer, you will need to activate it. That is, you need to tell the software that you are the rightful license holder. Depending on the McAfee software version, the steps may vary slightly. Many antivirus products have an area within the software where you manually key in the license code that you were given at the time of purchase. In the case of McAfee Total Protection 2009, you must create an online account and verify licensing via this account. In addition to verifying the licensing, this account entitles you to regular, automatic updates which are crucial.
To verify the McAfee license in Total Protection 2009 on the third computer, look for the McAfee "M" icon in the System Tray (the area in the lower right corner of your computer screen containing the clock). Right-click this icon and choose Verify Subscription. This will take you to the online account area where your third computer's antivirus protection will then be verified and activated.
As always, make sure that each of your computers is set up so that it is automatically updated with the latest antivirus definitions from McAfee.