I held off on Windows 10 for as long as I could until my job required it. Now this nonsense. I hope this isn't the start of them joining on the web DRM bandwagon.
I had that exact problem when trying to activate my copy of CS6 (physical, too). I just couldn't find a license key anywhere. The ones that I did find never worked. That was 4 years ago, so I don't know if I could do it again with success.