Again, it's still under a FLOSS license. you can use it for free as in beer, under the terms of the license. If you want further expectations satisfied (i.e. ongoing maintenance of the software), that's what money is paid for. You're not paying for the software, you're paying for services around it. (and the nice thing with Open Source is that if the original creator isn't available for whatever reason, you can pay somebody else for them, which is a lot harder with not-open software)