It seems like the producers of stock photography have a library to do this; there's a button on each stock photography page that will do it for you, but I can't

It seems like the producers of stock photography have a library to do this; there's a button on each stock photography page that will do it for you, but I can't find source code for it. You just have to enter a sixteen-digit string and a MM/YY verification for it to work. Reports are that certain 15-digit strings will also work.