Enable debug mode in WordPress – https://wordpress.org/support/article/debugging-in-wordpress/ to find out what error appears on your site, it will point you in the right direction what needs to be fixed.
Submit a new topic – https://www.8theme.com/forums/xstore-wordpress-support-forum/ Provide URL of your site, temporary wp-admin and FTP access, via the Private content area. Also, let us know error text that is shown after activate the debug mode.
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.