Once an OEM licence is registered against the device (motherboard) it can be reinstalled to the same hardware as many times as you like.
Can I reuse my OEM key?
Sorry, but no you can not. The biggest disadvantage of an OEM version is that its license is permanently tied to the first computer it’s installed on. It may never be moved to another.
Can you use OEM Windows more than once?
On preinstalled OEM installations, you can only install on one PC, but you there is no preset limit to the number of times that OEM software can be used.
Can I transfer an OEM license to another computer?
From an OEM Windows 7, Windows 8, or 8.1 licenses upgrade, these are licenses that come preinstalled on a new computer from a manufacturer, and then your Windows 10 license maintains the OEM rights – cannot be transferred. If you have a full retail copy of Windows 10, you can transfer it as many times as you want.
Can Windows 10 OEM be transferred to another computer?
Was this reply helpful? An OEM licence is bound to the device it was originally installed on, as it was provided by the manufacturer. It cannot be transferred to a new device, as it seems you have been told.