- Sign in at platform.openai.com → Settings → API keys.
- Click Create new secret key → copy it and store securely (you can set key permissions if needed). ([platform.openai.com][1])
- Go to Settings → Billing → Overview.
- Click Add payment details and add a standard credit/debit card.
- Choose $5 as the initial credit purchase → Confirm. (Minimum prepaid purchase is $5.) ([OpenAI Help Center][2])