license conditions for website developers

I am a website developer and i want to built eccommerce carts for clients using nopcommerce.
I am ready not to remove nopcommerce text link from each page as per terms of nopcommerce

But i need to customize the carts as per my clients requirements

I have checked nopcommerce licensing terms and they say its GPL 3.0

and this is what the first line of GPL 3.0 says

"Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed."


so my question is can i not customize the carts according to my client requirements.
Or i need purchase license for this.

Or USING, DISTRIBUTING, CUSTOMIZE DISTRIBUTING all is free with a condition that nopcommerce link is not removed

[email protected] wrote:
It's not GPLv3. It's nopCommerce Public License Version 3.0 ("NPL"). NPL is based on GPLv3 + the "powered by nopCommerce" text requirement.

[email protected] wrote:
Yes, you can customize and distribute it. But if you want to remove "powered by nopcommerce" text, then you need the copyright removal key (for each store URL using it)