Lost or forgotten your Windows activation key? Below we will see how you can recover the product key from an installed Windows 10, Windows 8 or Windows 7 operating system, with one command.
It is the simplest solution to find your product key from a Windows operating system already installed on your computer without using any third-party software. 
You will need to open a command prompt window and run the following command.
To open a command prompt window, search for “cmd” or “cmd.exe”, and open the black icon that appears first in the search results.
Type the following command:
wmic path softwarelicensingservice get OA3xOriginalProductKey
It will show you the product key of your operating system.
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Information:
In case the above command does not work on your system, open a txt document (notepad) and copy and paste the following text:
Option Explicit Dim objshell,path,DigitalID, Result Set objshell = CreateObject("WScript.Shell") 'Set registry key path Path = "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\" 'Registry key value DigitalID = objshell.RegRead(Path & "DigitalProductId") Dim ProductName,ProductID,ProductKey,ProductData 'Get ProductName, ProductID, ProductKey ProductName = "Product Name: " & objshell.RegRead(Path & "ProductName") ProductID = " ID: " & objshell.RegRead(Path & "ProductID") ProductKey = "Installed Key: " & ConvertToKey(DigitalID) ProductData = ProductName & vbNewLine & ProductID & vbNewLine & ProductKey 'Show messbox if save to a file If vbYes = MsgBox(ProductData & vblf & vblf & "Save to a file?", vbYesNo + vbQuestion, "BackUp Windows Key Information") then Save ProductData End If 'Convert binary to chars Function ConvertToKey(Key) Const KeyOffset = 52 Dim isWin8, Maps, i, j, Current, KeyOutput, Last, keypart1, insert 'Check if OS is Windows 8 isWin8 = (Key(66) \ 6) And 1 Key(66) = (Key(66) And &HF7) Or ((isWin8 And 2) * 4) i = 24 Maps = "BCDFGHJKMPQRTVWXY2346789" Do Current= 0 j = 14 Do Current = Current* 256 Current = Key(j + KeyOffset) + Current Key(j + KeyOffset) = (Current \ 24) Current=Current Mod 24 j = j -1 Loop While j >= 0 i = i -1 KeyOutput = Mid(Maps,Current+ 1, 1) & KeyOutput Last = Current Loop While i >= 0 If (isWin8 = 1) Then keypart1 = Mid(KeyOutput, 2, 1) Last) insert = "N" KeyOutput = Replace(KeyOutput, keypart1, keypart1 & insert, 2, 1, 0) If Last = 0 Then KeyOutput = insert & KeyOutput End If ConvertToKey = Mid(KeyOutput, 1, 5) & "-" & Mid(KeyOutput, 6, 5) & "-" & Mid(KeyOutput, 11, 5) & "-" & Mid(KeyOutput, 16, 5) & "-" & Mid(KeyOutput, 16, 5) 21, 5) End Function 'Save data to a file Function Save(Data) Dim fso, fName, txt,objshell,UserName Set objshell = CreateObject("wscript.shell") 'Get current user name UserName = objshell.ExpandEnvironmentStrings("%UserName%") 'Create a text file on desktop fName = "C:\Users\" & UserName & "\Desktop\WindowsKeyInfo.txt" Set fso = CreateObject("Scripting.FileSystemObject") Set txt fso.CreateTextFile(fName) txt.Writeline Data txt.Close End Function
Save it to your computer's desktop with the extension .vbs. You can use any name you want, for example iguru.vbs.
Below you can download the ready file. Open the .zip and double click on the iguru.vbs file. It will tell you your operating system key.
