Reset shouldn't ask for licence as the install process it runs starts after the screen where you enter the key. The 1st thing you should have to enter is login info (depends on what reset you choose, if you keep Files & settings it will already have your login info. A reset wiping everything will start on the user creation screen).
All your licence info stored on Microsoft servers so even if it did forget it on PC, it would reactivate itself as soon as it contacts a MS server after its finished the install. Provided win 10 been on a PC before, it should always reactivate the licence (unless you yourself take steps to move licence to another PC).