Hi Tony!
Licensing for W3 Total Cache Pro is on a “per-install” basis. That means if you’re using WordPress Multisite for your websites, you’ll only need one license for the network. If your sites are separate installations, you’ll need a license for each site. If you’re interested in Pro for multiple sites, contact our sales team directly from your WordPress Dashboard by navigating to Performance > Support > Sales Questions and we’ll be happy to come up with a solution that fits your needs.
We also have a 30 day money back guarantee on W3 Total Cache Pro licenses just in case you decide you don’t need the additional features offered in the Pro version.
Please let us know if you have any other questions for us!