Only the antivirus is free, and only in the most basic version, and only for home use. If you want the spyware product or the firewall, or the more sophisticated antivirus, or to use it at work, you’ll have to pay for it.
So if you are using those, then purchase it from Grisoft, its creators, rather than from "my cousin who fixes computers" where the money may or may not go to the ones who created it.