Hello Herb,
Thank you for your question and I am happy to answer.
W3 Total Cache Pro license is not necessary for the Redis Caching method. In other words, this is not a Pro feature. If you are on shared hosting, then memory-based caching like Redis is likely to be unavailable for you.
In order to use Redis via W3 Total Cache, you need to install PHP Redis extension on your server, so I would advise reaching out to your hosting support for assistance with this.
In case you still want to try out the Pro version of the plugin, we are offering a 30-day money-back guarantee.
Thanks!