First of all, Please make sure that your server requirements must meet the theme and plugins requirements as shown in this screenshot: https://postimg.cc/FdZMrDtK
And then Please try to deactivate and then reactivate the theme again with the same purchase code and then try to update.
If the issue will still persist then please delete the particular plugin and try to Install the latest version again.
Otherwise, please share your site WP Admin URL and Credentials with me here in the private content area of this topic by following the below-listed format, so that I will further check it for you on your site and help you out, Please also let me know the plugins name not updating on your site and giving error.
WP Admin URL:
WP Admin Username:
WP Admin Password:
Regards 8Themes Team.
One standard license is valid only for 1 project. Running multiple projects on a single license is a copyright violation.