If your device came pre-installed with Windows Pro, the product key is typically embedded in the system firmware (UEFI/BIOS), and Windows should activate automatically once connected to the internet. You can check your activation status by going to Settings > Update & Security > Activation. If it says, "Windows is activated with a digital license," you're all set.
If you upgraded to Windows Pro from another edition (like Home), the key would have been provided at the time of purchase—either via email, a physical card, or your Microsoft account. You can check your purchase history at account.microsoft.com under "Services & subscriptions."
In case you're reinstalling Windows and it's not activating automatically; you may need to retrieve the key using a third-party key finder tool or contact your device manufacturer if it was pre-installed.
Let me know if you need help checking your activation status or locating your purchase history. If this answer resolves your issue, feel free to hit "Accept Answer" so others can benefit too 😊