Not sure which provider you're using, but from what little information is public, most providers that offer an "all you can use for a flat fee" subscription are

Not sure which provider you're using, but from what little information is public, most providers that offer an "all you can use for a flat fee" subscription are losing money on every user. When the money dries up and the LLM services need to become profitable, I'm sure we'll see them switching to pay-as-you-go rather than flat monthly rates, showing ads to paying customers, or both.