Likely the Win 7 key is stored on your motherboard and you already have a license... Unless the repair shop had to swapboards.
We don't have much detail to go on...
Check to see if you have a key on your hardware with this utility:
ProduKey - Recover lost product key (CD-Key) of Windows/MS-Office/SQL Server If a Windows key is shown it is for whatever version your laptop shipped with. Windows 10 key resides in the cloud and will not be on your device. Write the key down or take a screen capture.
Begin your restore journey here:
https://forums.windowscentral.com/e?...token=RI2WjT9k
If you need additional help or have more questions or details to share, please join the site so you can reply in this thread. See
this link for instructions on how to join Windows Central.