Paste it in Fodide and confirm the domain
In Fodide, the same sheet: paste the key in Key. Fodide shows the domain the app will call (for example api.example.com). If it matches the service, turn on Send this key only to <domain>, tap Check, then Keep on this phone.
The key is sent only to that domain, only from your app's server, at most 120 calls a minute while you try the app. If the domain looks wrong, do not confirm; tell the agent.