Afaik, Windows "Home" is limited to 1, "Professional" to 2 and "Pro for Workstations" to 4 CPUs.
Can be nicely tested with virtualization (e.g. KVM). Just assign multiple CPUs with one core each and Windows will only use the amount of "CPUs" that the license allows. A single CPU with a bazillion cores is no problem, though.
I only know this because I ran into that exact pitfall several times already.