Hey Martin,
Thank you for reaching out to us!
Right now you have a Personal license for Events Calendar PRO, which grants you updates and support for a year on 1 site. To be able to use your license key on more sites, you can upgrade your license to Business by following the steps explained here:
https://theeventscalendar.com/knowledgebase/upgrading-a-license/
If you simply want to move your license key from one site to another, please follow these instructions:
https://theeventscalendar.com/knowledgebase/moving-your-license-keys/
I hope this helps! If you have any other questions at all please feel free to let me know and I’d be happy to help as best I can!
Cheers,
Patricia