Yes. The free HappenBoard plugin needs no licence key and has no time limit. It includes the events calendar, recurring events, and free sign-ups with a seat limit and email reminders. It also has appointment booking, imports from other event plugins, the iCal feed and Event schema for Google search results.
HappenBoard Pro is a paid add-on that you install on top of the free plugin. It adds paid tickets, QR code check-in, Google and Outlook Calendar sync, custom fields, extra display blocks and more. What Pro adds lists everything, and the pricing page shows the prices.
The Pro licence gives you updates, security fixes included. Every Pro feature keeps working without it, even after your licence expires. See installing HappenBoard Pro to activate it.