Bethesda.net is a digital distribution, digital rights management, multiplayer and communications service owned by Bethesda Softworks LLC. Platform provides features similar to those owned by Valve, Ubisoft or EA. Service id provided exclusively on PC. Bethesda.net has it’s own client which is mostly used by first-party games developed or published by Bethesda. Bethesda.net launcher debuted in 2016 granting access to multiplayer features and free games such as Quake Champions or Fallout Shelter.
Navigate to your Bethesda.net account and sign in (be sure you're signing in with the account you want to redeem the code with).
Click Redeem Code on the left side of the screen.
Enter your code and click Redeem.