Save way to request JSON serverside

Hello,
My goal is to create a simple “login” system, the player connects to server and enters a password and a username, the server sends the data via HTTP Request (GET) to a url (example: http://mywebsite.com/game/checkusername?user=john&password=bla&apikey=3948324). Now I have the following question: I want to execute this “check” server-side in the gamemode bp, but I am unsure about the “apikey” (The Request needs an Apikey to verify that it is authorised to do this request)… I want to save it as variable (not replicated) inside the Gamemode. Do players have access to the default value of a string variable in the Gamemode at some point? I’m using a dedicated server and the clients never have access to the dedicated server files, but arent these variables with their default value shipped with the released game?