$KmsServer = 'servername'
$map = 'BCDFGHJKMPQRTVWXY2346789' 
$value = (Get-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion').digitalproductid[0x34..0x42]  
$ProductKey = ''  
for ($i = 24; $i -ge 0; $i--) 
{ 
    $r = 0 
    for ($j = 14; $j -ge 0; $j--) 
    { 
        $r = ($r * 256) -bxor $value[$j] 
        $value[$j] = [math]::Floor([double]($r/24)) 
        $r = $r % 24 
    } 
    $ProductKey = $map[$r] + $ProductKey 
    if (($i % 5) -eq 0 -and $i -ne 0) 
    {
        $ProductKey = '-' + $ProductKey
    } 
} 

slmgr.vbs -skms $KmsServer
slmgr.vbs /ipk $ProductKey