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 you use OEM key more than once?
Note 1: You can only use the OEM key on one computer, OEM can not be moved to another computer.
Can you use an OEM key on another computer?
Nope. two things: OEM licenses cannot be transferred.
How many times can Windows 10 product key be used?
You can only use a Windows 10 key once on a PC or laptop. If you need to reinstall the operating system for any reason, you’ll need to enter the key again.
Do OEM Windows 10 keys expire?
No OEM keys do not expire for the lifetime of the device.