If Windows 7 is currently installed and activated, you can use tools like Belarc Advisor or ProduKey to retrieve the key from the system registry.
Since Microsoft stopped direct sales, you must rely on third-party retailers or existing hardware:
If you already own a computer that had Windows 7, you might not need to buy a new key: buy microsoft 7 product key
If online activation fails, you can use the method by running slui 4 in the Run dialog (Win+R). How to get your product key for Windows 7/8/10
You can sometimes find unused OEM or "System Builder" retail packages on sites like Amazon or through specialty software vendors. Prices for these can range from approximately $50 to over $100 depending on the edition (e.g., Professional or Ultimate). If Windows 7 is currently installed and activated,
Finding a legitimate Windows 7 product key is difficult today because Microsoft ended mainstream support for the operating system in 2015 and extended support in 2020. As a result, Microsoft no longer sells Windows 7 licenses directly. Where to Buy a Windows 7 Product Key
Once you have a valid 25-character key, you can activate it by: Right-clicking and selecting Properties . Clicking Change product key at the bottom of the window. Entering your key and following the prompts. Prices for these can range from approximately $50
Some licenses are specifically sold for refurbished PCs and may be available at lower costs, often around $50.