Hello,
Thank you so much for purchasing our theme and contacting our support center.
As we can see, your purchase code is already activated. If you want to activate it again, you need to remove all the activations in your account first. You can do this on this page https://xtemos.com/my-account/
After this, you will be able to activate the theme with your purchase code without any issues. Note that you can activate it twice: one on your development website and one on the production.
Kind Regards