PowerShell: Gets SharePoint License Key for SharePoint Server 2007, 2010, or 2013.

Get-SPLicenseKey.ps1

<#
.SYNOPSIS 
    Gets the SharePoint License Key for 2007, 2010, or 2013

.DESCRIPTION
    Gets the SharePoint License Key for 2007, 2010, or 2013.  

.PARAMETER version
    Version of SharePoint installed.

.EXAMPLE
    Get-SPLicenseKey 2013
    Get-SPLicenseKey -version 2010
    Get-SPLicenseKey 2007

.NOTES
    AUTHOR: System Center Automation Team
    LASTEDIT: Dec 18, 2014 
#>
Param(
    [Parameter(Mandatory=$True,Position=1)]
    [string]
    $version
)


$map = "BCDFGHJKMPQRTVWXY2346789"
$property = @{"2007"="12.0";"2010"="14.0";"2013"="15.0"}

# Get Property
$value = (get-itemproperty "HKLM:\SOFTWARE\Microsoft\Office\$($property[$version])\Registration\{90$(($property[$version] -replace '\.',''))000-110D-0000-1000-0000000FF1CE}").digitalproductid[0x34..0x42] 

# Begin Parsing
$ProductKey = "" 
for ($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
    }
}

$ProductKey

how can i run this ps1 file? pls help