Hey Wee Yang,
Great question. You can transfer your plugin license from one site to another anytime by following the steps outlined in this post:
https://theeventscalendar.com/knowledgebase/moving-your-license-keys/
That will allow you to access both plugin updates and support for the site that you move the license to. The site that used to have the license will continue to work but will not have access to plugin updates or support. You can however, manually install the plugin updates, if needed.
Does this help explain things a bit? Please let me know. 🙂
Cheers!
Geoff