ShowKeyPlus is a portable freeware app to retrieve and save your Windows product key if you lost it.
Losing your Windows product key can cost you hundreds of dollars if you can't find it. Luckily, there are quite a few utilities like this one that can find your key if you lost your DVD or if you can't read the product key on one of your stickers, for example.
ShowKeyPlus will retrieve your product version or name (Windows 10 Pro, for example), the product ID, the currently installed key, and the OEM key, if applicable. You can then save the information found in a text file that you can backup, print, or whatever you like.
Optionally, ShowKeyPlus can also retrieve your key from backup if you have a Windows folder from the installation. It can also check that your product key is valid with your edition of Windows.
It can find the following keys: OEM: DM, OEM: SLP, OEM: NONSLP, OEM: COA, Retail = Full Packaged Product (FPP), Volume: MAK = Multiple Activation Key, Volume: GVLK = Group Volume License Key, and WAU = Windows Anytime Upgrade. It will not retrieve MAK keys because those are intentionally hidden to prevent pirating of those keys.
You can find dozens of utilities that only retrieve your product key. However, ShowKeyPlus stands out with its ability to save and verify your product key. Please note your security software will flag almost every key finding utility.