Why do long conversations cost more per message?

On a paid AI model, a message costs its listed price while the conversation is short, and a little more as it grows, because the AI model reads more of it each time. The most a message can cost is the price of the Memory you chose, which Switch model shows as a range such as “1–10 credits / message”. A smaller Memory keeps long chats cheaper, and a larger one remembers more word for word. Free AI models are free at every Memory size. Some Dochi models are an exception: they are free for short chats and charge for their larger Memory sizes, shown as a range such as “Free–5 credits / message”.