Follow the below steps:
- Go to the Account tab of the plugin (staging site).
 - Click on the Remove License Key button (This will free your license from the existing instance) – Refer to the image below
 - Now you can use your license on the production site.
 

If the problem persists, please get in touch with us at joomlasupport@xecurify.com or Click here to contact us for support. It would be helpful if you could share your use case with us.