You need to update the theme to the latest version (6.2.4). Never update XStore Core plugin without theme update. Follow this article to update the theme – https://xstore.helpscoutdocs.com/article/63-theme-update
Our changelog you can find here – https://xstore.8theme.com/update-history/
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.