How can I get Windows Product Key from Active Directory Users Machine

Dear all,  How can I get Windows Product Key from Active Directory Users Machine via power shell or any tools?  In our company, we have 300 PC. Somehow they lost Windows product keys. So now they want all users machine windows product keys. Is it not possible to go physically all end users and in that case i can't use also key finder software. Company authority assigned me to find a way get windows product key for all machines but I am unable to find this. Any one can help me about this.Thanks in advanced.

 

Thanks

Hosen