Lost or forgot your Windows activation key? Below we will see how you can retrieve the product key from an installed Window 10, Window 8 or Window 7 with one command.
It is the simplest solution to find your product key from a Windows operating system that is already installed on your computer without using any third party software. 
You should 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 will appear first in 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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Update:
If the above command does not work on your system, open a 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 = "Product ID:" & objshell. RegRead (Path & "ProductID") ProductKey = "Installed Key:" & ConvertToKey (DigitalID) ProductData = ProductName & vbNewLine & ProductID & vbNewLine & ProductKey 'Show messbox if save to 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, 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, 21, 5) End Function 'Save data to a file Function Save (Date) 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 \ WindowsKeyI nfo.txt "Set fso = CreateObject (" Scripting.FileSystemObject ") Set txt = fso.CreateTextFile (fName) txt.Writeline Data txt.Close End Function
Save it to your desktop with the extension .vbs. You can use a name you want, for example, iguru.vbs.
Below you can download the file. Open .zip and double-click the file iguru.vbs. It will tell you the key of your operating system.
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