Help with License terms, please

Hello,
I don't understand the license terms.
Please help me.
I've looked for the terms in english and in french, and I don't understand.
I make a php website to a client, and I'll be paid for it.
I need to let the client update the content of the site with a WYSIWYG editor. He has to log with the admin login and password, and he can update the php files.
If I use FCKEditor, can I use it without paying the CDL license ?
I've read all the things by searching on the forum, but I'm not sure to understand all.

Sorry for my poor english (I'm french).

Regards
Loma