Hi,
Thanks for using our plugins. I can help out here.
The license is only needed for Automatic Updates. All our plugins will work without having a license.
So you can choose the site you want to have the automatic updates and if you have a development site you can manually update that one or transfer the license back and forth.
For all our information related to the license please review this guides:
https://theeventscalendar.com/knowledgebase-category/purchase-install/
Let me know if you have any follow up questions.
Thanks