Because the exact location of a product key depends on the individual product, users must check different locations. Some of the possibilities are: the back or inside of the disc box, on the bottom of a laptop, within the BIOS, or in the Library section of Steam.
If you purchased an application or a video game from a retailer, it is very likely that the license key is either on the back of the disc box or inside it. You may need to scratch a protective label to be able to see the license key. In that case, do so very carefully to avoid destroying the key.
If looking for a Windows license key on a laptop that came with Windows 7 or older, you are very likely to find it on a sticker on the bottom of the laptop. If there is a compartment that you can open, the key may be inside. The license key is locked to your computer and may not activate Windows installations on other computers. It is a good idea to take a picture of the license key and store it in a safe place as it may rub off in time.
If using a computer that came with Windows 8 installed, the license key is within the BIOS. Download and launch RWEverything. Click the ACPI icon on the toolbar, and open the MSDM table. Wait for the application to scan your system. The key at the bottom is your Windows license key.
If looking for the key of a game you purchased on Steam, click Library on the menu bar at the top, and click Games. Right click on the game in the list on the left, and click View Game CD Key. Steam then displays the license key in a new window.