When I license a photo at Adobe stock, do I have to add an image proof - and - Where I have to place this on a website?
Not sure what you mean by an Image Proof in this case? Do you mean an image credit?
No, I mean the details of the photographer and the agency. Do I need to do this on a website and if so, where?
No, it isn't required unless you use it on Social Media such as Facebook or Twitter.