Hey Peter,
You can use Eventbrite tickets and any other add-on with just the free version of The Events Calendar.
Events Calendar Pro is not required for any add-on, including Eventbrite Tickets.
As for whether Eventbrite Tickets is the right choice for you, that’s something that is hard for me to say; it’s a great add-on and if you would prefer to sell tickets through Eventbrite.com, it’s our only add-on that does so.
If, however, you would like to sell the tickets directly from your site and thus keep 100% of the revenues (because selling on Eventbrite.com means that they take a cut of the sales), then you can use our WooCommerce Tickets add-on instead or a similar add-on.
Check out all of our Ticketing add-ons, with more information about each of them, here → http://theeventscalendar.com/tickets
I hope that helps!
— George