They have. Look in your account, it's in usage. If your usage exceeds what you have paid you will get told.

This said, it's a good offer. You can switch between many models quickly. They are rated by quality, speed and price, and it's shown with orange dollar symbols for price and bullets for speed and quality. Example:

    Anthropic Claude Opus 5.5

    Anthropic's flagship model with always-on adaptive
    thinking ($$$$$). Best for deep reasoning, agentic
    coding, and long-horizon work.

    Cost    $$$$$
    Quality ●●●●●
    Speed   ●●