Take my apologies for the delay in answering.
You did not provide link to your site.
To change the site language go to Settings > General > Language. To translate theme and XStore core plugin follow the documentation https://xstore.helpscoutdocs.com/article/30-base-theme-translation
try to find the language menu but i didn0t find,
Do you want to create a multilanguage site? Then you need an additional plugin https://colorlib.com/wp/wordpress-multilingual-plugins/
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.