Windows 8.1 OEM key available from Retail ISO source
Windows 8.1 OEM key available from Retail ISO source
from various discussions it seems you can get an OEM key via a retail DVD/ISO, but using it won’t let you upgrade—it requires a clean install and even then needs a retail key. This explains why Microsoft’s direct download assumes upgrading to Windows 8.1, which OEM keys can’t handle. OEM keys work well between machines, though; however, using an old OS version will deactivate it. Unlike Windows 7 or XP (the details are unclear), retail keys are mostly non-transferable except for OEM ones, which remain permanent. This is quite confusing based on all the mixed information I’ve seen online.
Speedbird is the right person to reach for activation and product keys.
Absolutely, it will function. You're no longer on XP; any key from the same version should work.