Hello there
I have made 10 T-shirt designs for one of my client last year and he is selling these design on a plat form. But now the platform has asked him to provide the proof that he have the rights to use those designs. So he has asked me to provide some documents that it must be written that he has the rights to use those designs commercially for merch. He is asking for something like this (attached document).
I am also willing to provide him the document but I don't know how to make a proper professional copyright document so that he has the license to use those designs commercially for merch. Can anyone help with this regard.
licence__309212.pdf