We recommend getting started with the free version of a plugin just so you can see how it works and what it has to say about the current state of our site. Eventually, you will probably want to turn to a premium version so you can access more advanced features and keep track of your site’s progress and growth with greater detail. But don’t rush into spending any money — the plugin developers will always be happy to take your payment at a later date once you have confirmed that you are on the right track.