Most of the time the computer or laptop came with W10 pre-installed. In this case, you can install it from USB flash memory when the computer gets crashed. Then you need to create a Windows 10 installation media from another computer, but you can create now for a future issue. I share it the information below:
Take into account that must be the same W10 version, because you can get trouble with the activation; Ex your computer came with Windows10 home you must install this version, not Profesional.
Also in that scenario, the license key is embedded in your motherboard and it is now a digital license. You can reinstall it as many time as you want, but if you change the hardware you need to be prepared, see the following link:
The Activation troubleshooter could help If you’re unable to activate Windows 10. To use it, select Start > Settings > Update & Security > Activation , and then select Troubleshoot .
You must be signed in as an administrator to use this option. The Troubleshoot option is available only for Windows 10 Version 1607 or later. Once you activate, the option disappears.