Hi, Juggler Design. Thanks for your interest in our plugin suite.
Whomever buys the item(s) will be the one to login to obtain the plugin install .zip file(s). Sometimes consultants prefer to buy it themselves, such as if you have 7 clients using Events Calendar PRO, you could buy the Agency level license (10 sites) and use the same license key across all your client sites. Other times, they prefer the client to buy their own so the client can login to our Help Desk and ask questions themselves.
Please reference https://theeventscalendar.com/knowledgebase/new-user-primer-the-events-calendar-and-events-calendar-pro/ and let me know if you have any follow-up questions on this topic.
Last but not least, we have Bundles and a pretty great Refund Policy so you can buy one or many of our add-ons and thoroughly test them.