If I wanted to pay for a plugin, I'd go searching for one. I'm not looking to install a free plugin from the WordPress CMS only to have it blocked pending purchase of another service. Overview and installation notes lead you to believe that the plugin works upon installing it. Surprise! There's a big spammy ad at the top of the page insisting you buy a membership/subscription and the quick-insert button asks for a code that you can only get from this service.