Copyright Contract Theme

Hi there.
I’m writing a contract for my website creation service using themeforest themes. I have reached the point where I need to write the “copyright”. What should I need to write?

The theme you’re using comes with a license ( usually inside of the zip, license.txt )
You can check that file as well as TF License and/or TF Terms page

Ok, is this statement right?

"
COPYRIGHT
The template author retains ownership of the template but grants the license to the Customer under these terms. Components inside the site made by the customer and/or third parties are not owned by the Supplier who will not disclose any information or documents but will use them only for the purpose of carrying out the work inside the site. The Customer is not allowed to extract a part and use it separately from the Final Product created using that part for other purposes. The site is sublicensed anywhere in the final product. The sublicense is granted only on condition that the use of the product is limited to use the final site, therefore any part of it cannot be extracted, reproduced or used in any other way (Limited sublicense)."

Even though it sounds okay, to make sure everything is OK, in legal terms, you should contact a lawyer.