Hello
Did you purchase this PC from big manufacturer like Dell, HP, etc, or is it from builder?
If it is from big manufacturer, your license should be already embedded in the motherboard of the key is not necessary.
But if it is from builder, then license is typically OEM-NSLP. In this case, you do need the key, but you need the support from builder instead for OEM type, they can then get support from Microsoft via Partner Center. It is kind of wholesale vs. retail concept.