I made a library with which I distribute an opensource-licences-readme.txt file disclosing which open-source projects I have leveraged and including their copyright notices and other required info.
I was asked by a company that wants to use my library today if they also need to include this .txt file in their product (theirs is a compiled commercial product for sale). I'm unsure if it's just me that needs to do so, or if they are obliged to copy and redistribute the same license information that I provide, so I haven't been able to advise them.