It's a good idea to take before and after photos of work you perform. In addition to my real estate company, I have a remodeling company, too. We take before and after photos for a "brag book" to help new customers see what's possible.
Another reason is that it shows the condition the work was in when finished. For example, we took our usual photos after installing a set of commercial doors at a very busy, famous ice cream shop on Chicago's south side. Month's later, we got a letter from an attorney saying we were being sued because a very tall man struck his head on the closer on the door. Our photos showed the closers installed correctly above the door jamb. Someone flipped it upside down (amazing it still worked) after the installation. Because we had the photos, we were able to successfully defend ourselves.
In another instance, we had before photos of a door the owner insisted had a brass threshold. He signed off on the details of the door order, which included a matching aluminum threshold. The photos clearly show the old door had aluminum.
Publishing the photos on a website may be a gray area in your jurisdiction, although I doubt it. We've included language in our contracts that allow us to publish photos in advertising of any kind for up to a year.
Finally, it's always good to just ask. Explain that you take before and after photos to show the transformation. Be proud of your work! Show it off on your website and social media. One final bit of advice, put a watermark on your photos to keep others in your industry from using your work on THEIR advertising.