Hi Paul,
Thanks for getting in touch!
You can absolutely use the same license for a development and live site. There are some restrictions on how that works, but here’s more information on how that works:
https://theeventscalendar.com/knowledgebase/using-one-license-live-dev-sites/
It’s also worth noting that it is not necessary to enter the license in order for the plugin to work. The license only activates automatic updates and provides you with access to support. Otherwise, the plugin will be fully functional.
Does this help answer your question? Please let me know. 🙂
Cheers!
Geoff