Installing Windows 10 on a Blank Drive

You don't need to buy anything to reinstall Windows 10. Use Microsoft Media Creation Tool to create the installer on a flash drive, boot from that flash drive and begin the installation process.

I wrote a detailed description of how to install Windows 10 and 11. It may help you.

Here's another description of the install process, from a Microsoft MVP.

If this is the older latitude you posted about elsewhere, it would be prudent to run hardware tests on the laptop and drive first. Run Dell Diagnostics:
Immediately after pressing the power button to turn on the laptop (or after clicking the Reboot command), press and hold (or repeatedly press) F12 to enter the One Time Boot Menu, select Diagnostics and press Enter. The Dell Diagnostics will test major hardware components. Choose to run the extended tests.

To be absolutely safest, I recommend first performing an in-place upgrade from 7 to 10, then checking that Windows 10 is activated. If it's activated, then I would proceed to clean install Windows 10.

However, if you have drive errors that make that impossible, you should be able to clean install Windows 10 and at the appropriate point you would enter your Windows 7 Product Key.