How to retrieve product key for Windows 8.1?

If you have lost the packaging for the product, they you cannot get the key from there.

Try this, if your PC is bootable.

http://www.intowindows.com/how-to-recover-windows-78-1-product-key-without-using-third-party-tools/

How To Recover Windows 7/8.1 Product Key Without Using Third-Party Tools

admin Updated on Sep 26th, 2013

If it is not bootable, you will have to use a third party tool.

http://www.7tutorials.com/how-recover-your-lost-windows-7-or-windows-8-product-key

How to Recover Your Lost Windows 7 or Windows 8 Product Key

Thanks - this was really helpful, but I did have two small problems with it:

1. When the script is copied and pasted as described here, it gets a couple of syntax errors (at least when copied from IE):
   • Some double-quotes are replaced by '?' (in addition, the double-quotes are not the basic ASCII / typewriter form, but come in left and right versions. I do not know if it mattered, but I replaced them all with simple non-directional double quotes ( " ).)
   • The '--' operator in the 'for' expressions is replaced by a single '-'.
2. You instruct the administrator to change (and probably weaken) the security policy, in order to load and run the script, but not to restore it afterwards, or to use Get-ExecutionPolicy to make note of what it was initially. If you do Set-ExecutionPolicy  RemoteSigned -scope Process, the change will apply only while the current shell process is running, and only within that shell.; see https://technet.microsoft.com/en-us/library/hh849812.aspx .)

This is the function definition - it may be easier to copy it accurately from here (note that the line beginning '$charsArray =' has been wrapped onto three lines in this post; however, when I tried copying it from this post, it pasted correctly as a single line.)

function Get-WindowsKey {
 ## function to retrieve the Windows Product Key from any PC
 ## by Jakob Bindslet (*** Email address is removed for privacy ***)
 param ($targets = ".")
 $hklm = 2147483650
 $regPath = "Software\Microsoft\Windows NT\CurrentVersion"
$regValue = "DigitalProductId"
Foreach ($target in $targets) {
 $productKey = $null
 $win32os = $null
 $wmi = [WMIClass]"\\$target\root\default:stdRegProv"
$data = $wmi.GetBinaryValue($hklm,$regPath,$regValue)
 $binArray = ($data.uValue)[52..66]
 $charsArray = "B","C","D","F","G","H","J","K","M","P","Q","R","T","V","W","X","Y","2","3","4","6","7","8","9"
 ## decrypt base24 encoded binary data
 For ($i = 24; $i -ge 0; $i--) {
 $k = 0
 For ($j = 14; $j -ge 0; $j--) {
 $k = $k * 256 -bxor $binArray[$j]
 $binArray[$j] = [math]::truncate($k / 24)
 $k = $k % 24
 }
 $productKey = $charsArray[$k] + $productKey
 If (($i % 5 -eq 0) -and ($i -ne 0)) {
 $productKey = "-" + $productKey
 }
 }
 $win32os = Get-WmiObject Win32_OperatingSystem -computer $target
 $obj = New-Object Object
 $obj | Add-Member Noteproperty Computer -value $target
 $obj | Add-Member Noteproperty Caption -value $win32os.Caption
 $obj | Add-Member Noteproperty CSDVersion -value $win32os.CSDVersion
 $obj | Add-Member Noteproperty OSArch -value $win32os.OSArchitecture
 $obj | Add-Member Noteproperty BuildNumber -value $win32os.BuildNumber
 $obj | Add-Member Noteproperty RegisteredTo -value $win32os.RegisteredUser
 $obj | Add-Member Noteproperty ProductID -value $win32os.SerialNumber
 $obj | Add-Member Noteproperty ProductKey -value $productkey
 $obj
 }
 }

is it necessary for my pc to be potable?

my pc says in red sentences that:-

Import-Module : The specified module 'C:\Users\PC\Desktop\RecoverKey.ps1' was not loaded because no valid module file
was found in any module directory.
At line:1 char:1
+ Import-Module C:\Users\PC\Desktop\RecoverKey.ps1; Get-WindowsKey
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ResourceUnavailable: (C:\Users\PC\Desktop\RecoverKey.ps1:String) [Import-Module], FileNo
   tFoundException
    + FullyQualifiedErrorId : Modules_ModuleNotFound,Microsoft.PowerShell.Commands.ImportModuleCommand

Get-WindowsKey : The term 'Get-WindowsKey' is not recognized as the name of a cmdlet, function, script file, or
operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try
again.
At line:1 char:51
+ Import-Module C:\Users\PC\Desktop\RecoverKey.ps1; Get-WindowsKey
+                                                   ~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (Get-WindowsKey:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException

i do not know what does this mean, but it is written that:-'get-windows key' is not recognised.

after completion of the final step

please help me please!