I just downloaded and created a Windows 8.1 Pro ISO image from the Media Creation Tool and it tells me to copy the product ID I am unable to find this the procedure I used was to download the Tool then download the files to build the ISO and then burn it which did not work for some reason, so I burned the ISO manually thru Windows ISO maker which worked but how can I find the Product key?

In that case it depends how you originally got 8.0.
If 8.0 came originally pre-installed on your computer, and you are download the 8.1 media as a way to easily update that computer, no key is needed (it's stored in the PC hardware itself and detected automatically).
If 8.0 was something you purchased at the store (online or real building store), the 8.0 key will work with 8.1. This is something entirely new that's only possible over the past week or so (I heard details about it on the latest Windows Weekly podcast).