In their README.txt, under section attribution, they demand:
"If you use ChemDoodle Web Components in your website or product, we request that you provide a link on your site to web.ChemDoodle.com and/or www.ChemDoodle.com. When using the SketcherCanvas component, you are not allowed to remove any of our links or logos."
The following sentence is about service. Maybe, the whole attribution section is only required if some kind of support/service is wanted/called. The issue with the quoted sentences is that they are supposed to void GPL.