It can be used, yes, and will work and activate perfectly fine, but it is a violation of the licensing terms for non system builders to use Windows 7 OEM software. Windows 8 and Windows 8 Pro are the only versions of Windows that have a personal use license.
For compliance, Windows 7 retail is the only Windows 7 product Microsoft offers for non system builders to install onto a computer that does not already have an upgradeable version of Windows on it.