Fixed version of https://gallery.technet.microsoft.com/scriptcenter/Get-product-keys-of-local-83b4ce97/view/Discussions#content

Get-ProductKeyv2.ps1

function Get-ProductKey {
     <#   
    .SYNOPSIS   
        Retrieves the product key and OS information from a local or remote system/s.
         
    .DESCRIPTION   
        Retrieves the product key and OS information from a local or remote system/s. Queries of 64bit OS from a 32bit OS will result in 
        inaccurate data being returned for the Product Key. You must query a 64bit OS from a system running a 64bit OS.
        
    .PARAMETER Computername
        Name of the local or remote system/s.
         
    .NOTES   
        Original Author: Boe Prox
	Components taken direct from Jakob Bindslet (jakob@bindslet.dk)
	Small changes to make keys correct - Jordan Rinke
        Version: 1.1       
            -Update of function from http://powershell.com/cs/blogs/tips/archive/2012/04/30/getting-windows-product-key.aspx
            -Added capability to query more than one system
            -Supports remote system query
            -Supports querying 64bit OSes
            -Shows OS description and Version in output object
            -Error Handling
     
    .EXAMPLE 
     Get-ProductKey -Computername Server1
     
    OSDescription                                           Computername OSVersion ProductKey                   
    -------------                                           ------------ --------- ----------                   
    Microsoft(R) Windows(R) Server 2003, Enterprise Edition Server1       5.2.3790  bcdfg-hjklm-pqrtt-vwxyy-12345     
         
        Description 
        ----------- 
        Retrieves the product key information from 'Server1'
    #>         
    [cmdletbinding()]
    Param (
        [parameter(ValueFromPipeLine=$True,ValueFromPipeLineByPropertyName=$True)]
        [Alias("CN","__Server","IPAddress","Server")]
        [string[]]$Computername = $Env:Computername
    )
    Begin {   
        $map="BCDFGHJKMPQRTVWXY2346789" 
		$hklm = 2147483650
		$regPath = "Software\Microsoft\Windows NT\CurrentVersion"
		$regValue = "DigitalProductId"
    }
    Process {
        ForEach ($Computer in $Computername) {
            Write-Verbose ("{0}: Checking network availability" -f $Computer)
            If (Test-Connection -ComputerName $Computer -Count 1 -Quiet) {
                Try {
                    Write-Verbose ("{0}: Retrieving WMI OS information" -f $Computer)
                    $OS = Get-WmiObject -ComputerName $Computer Win32_OperatingSystem -ErrorAction Stop                
                } Catch {
                    $OS = New-Object PSObject -Property @{
                        Caption = $_.Exception.Message
                        Version = $_.Exception.Message
                    }
                }
                Try {
                    Write-Verbose ("{0}: Attempting remote registry access" -f $Computer)
					$remoteReg = [WMIClass]"\\$Computer\root\default:stdRegProv"
					$data = $remoteReg.GetBinaryValue($hklm,$regPath,$regValue)
					$value = ($data.uValue)[51..66]
                    $ProductKey = ""  
                    Write-Verbose ("{0}: Translating data into product key" -f $Computer)

                    for ($i = 24; $i -ge 0; $i--) { 
                      $r = 0 
                      for ($j = 14; $j -ge 1; $j--) { 
                        $r = ($r * 256) + $value[$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 
                      } 
                    }
                } Catch {
                    $ProductKey = $_.Exception.Message
                }
                $object = New-Object PSObject -Property @{
                    Computername = $Computer
                    ProductKey = $ProductKey
                    OSDescription = $os.Caption
                    OSVersion = $os.Version
                } 
                $object.pstypenames.insert(0,'ProductKey.Info')
                $object
            } Else {
                $object = New-Object PSObject -Property @{
                    Computername = $Computer
                    ProductKey = 'Unreachable'
                    OSDescription = 'Unreachable'
                    OSVersion = 'Unreachable'
                }  
                $object.pstypenames.insert(0,'ProductKey.Info')
                $object                           
            }
        }
    }
} 

Further testing shows this to be returning, unique, but incorrect data.

edit: Fixed, the loop and start point were off. Tested this on multiple machines and it is returning the proper key now (tested on server 2012 r2)

can we have version for server 2016?

coz its not working on server 2016

Hi Jordan

it is returning almost the correct data, the first 5 digits are wrong

your script is returning:
FFXTT-

and must be:

FXTNT-

the rest are okay.

is there any updated version?

thank you!