Hi Martin,
Thanks for reaching out. I’d be happy to help with your questions.
For migrating the tickets and attendees you can follow the process outlined here: https://theeventscalendar.com/knowledgebase/using-wordpress-export-tools-to-migrate-events-content/
I believe you should import the tickets first, then the attendees. Be sure to choose the post type for the specific type of tickets you have. There are separate ticket post types depending on your ecommerce plugin.
If you are moving to a new domain, you will need to remove the old domain by visiting your account license keys page before entering the license in the new site: https://theeventscalendar.com/license-keys/
There will be a “disconnect” link next to each URL the plugin is authorized on.
Once you have disconnected your old site, just reinstall the plugins on the new site, and enter your license keys in the Events > Settings > Licenses tab, and save.
Hope that helps! Please let me know if you have any additional questions.
Thanks,
Sky