cvs261
Did your computer come with Windows 7 Ultimate?
Most people use the terms product key and CD key interchangeably. If referred to on your computer case or bottom of a laptop it is Certificate of Authenticity COA. Irregardless, it is a 25 character alpha/numeric key 5 sets of 5.
If you use a key-finder such as magical jelly bean it is the CD key not Product ID.
If you look in control panel > system you will see Product Id listed if your system is showing activated, genuine Microsoft in the lower right corner, that is not the 25 character activation key, see link slightly below it.
Couple ways now that I would recommend, not off the internet.
This would be if you don't have COA on your computer and no key. Another same model, etc. computer such as the one you have running Win 7 Ultimate, not likely unless your machine came with ultimate. The is referred to as an OEM license, it is tied to the Motherboard has a Slick table. The Original Equipment Manufacturer license from M$ is for all that particular model of computer, in other words, a universal key.
A retail copy from say a friend that had it on a computer they no longer have in service & don't plan to. The key is checked against user by M$ to ensure it only has the number of valid activations. Office 2010 for example has licenses for 1, or 3, etc. at increasing prices but less than individual ones.
I made the transition to windows 10 Home but dual boot it with Win7x64.