I am a graphic designer who provided spec work for a client. I worked on a flyer and I gave them 2 options. They went with one, paid for it.
Now they have another project and would like to use the other preliminary draft from the last project. I gave them a quote (seeing as I would have to purchase photo under my license and adjust layout for text, etc.) The client decided they didn't want to pay for me to do the work, they just wanted to pay me for the use of the photo. Due to licensing restrictions, I am not able to re-sell the copyright. This photo, however is a concept that I came up with.
Should I turn over the link where they can find this image so that the client can purchase and let them use how they would like? I feel as they are wanting to use my design idea to make something similar without paying me. What is the correct, professional way to handle?