I am really sorry for such a late reply!
It seems your question somehow slipped through the cracks.
Premium themes sold on WordPress.com can be only used on WordPress.com. If you want to use the Luxury theme on a self-hosted WordPress site, then you have to purchase a license for the theme from here – https://organicthemes.com/theme/luxury-theme/
If you have any other questions, then please let me know. :)