I am not a lawyer.
Put your images on your own web site, with a notice that says exactly that:
Non-transferable license is granted to you, the downloader of this image, to use this image in any work or compilation, including commercial purposes.
Any time you grant license to someone else, they don't have authorization to transfer that license to anyone else, unless expressly granted in the license (with some exceptions, particularly where copyright law and contract law overlap).