Hello,
01. One regular license allows you to use our theme for a single project/website. For multiple projects, you need to purchase one regular license per domain/website. https://themeforest.net/licenses/terms/regular
If you want to move the license, You need to delete your old activation first and activate a new one. You can do this in your account on our website https://xtemos.com/my-account/
02. Please deactivate all the 3rd party plugins and activate only theme-required plugins on the site and then check the issue. I am sure your issue will be solved. Then Activate the 3rd party plugins one by one and check which plugin is creating the issue for you.
Best Regards.