Why your AI character forgets things, and what helps

Last updated September 18, 2026 · Any AI character chat app · By the developer of LonelyTavern

The short answer

• The AI does not remember your chat. The app reminds it every time. Each time you send a message, the app sends the AI your character's card and as much of the recent chat as fits. The AI reads that and writes its reply. It has nothing else.
• There is a limit to how much fits. This limit is called the context window. Once your chat is longer than the window, the oldest messages are left out. That is why the character seems to lose its memory somewhere around message 100, 300, or 400, depending on the app.
• You cannot make the window bigger, but you can use it better. Keep the character card short, write a summary of the story, and keep background details in a lorebook that loads only when they come up. Every app's memory feature is a version of one of these three ideas.

What is going on behind the scenes

• The AI starts from zero on every message. Nothing carries over from one reply to the next unless the app sends it again.
• Chats fill the window fast. The window is measured in tokens, and a token is about four characters. Fifty back-and-forth exchanges add up to about 20,000 tokens, which is more than most apps allow. So the oldest messages are the first to go.
• Chatting does not change the AI. A popular theory says long chats slowly overwrite the character. They do not. When your character drifts at message 60, it is because the messages that defined the character have dropped out of the window.
• A bigger window would not fix it. The app sends the whole window with every message, so a bigger window costs more on every turn. And AI models get worse at using a long window, not better.

What each symptom means

• The character forgets a name or a plot point from a while ago. That message has dropped out of the window. Put the fact back in a summary, a memory field, or a lorebook entry.
• The character repeats itself. The window is full of its own recent replies, and the AI copies what it sees most. Edit or delete the repeated lines.
• The character stops sounding like itself. The chat has pushed the character card aside, or the app has cut the card short. Make the card shorter.
• The character forgets something from three messages ago. This is not the window. Either the app is dropping far more than it should, or the AI model is too weak. Try the same thing in a fresh chat to tell which.

What helps, tonight

1. Shorten the character card. Every word in the card takes space that the chat could have used. Keep the card under about 1,500 tokens. The card guide says what to cut first.
2. Write the summary yourself. Most apps have a field for this, called memory, chat memory, or author's note. Put five short lines of facts in it, not a paragraph of story: where you are, what the relationship is now, and which plot threads are open.
3. Move backstory into a lorebook. A lorebook entry loads only when its trigger word appears in the chat. An entry about the character's brother costs nothing until someone says "brother". Keep each entry short, because a loaded entry takes space in the window like anything else.
4. When the character drifts, write a recap. Send one message, out of character and in brackets, with three sentences: where the story stands, and who the character is. Then carry on.
5. When the chat is too far gone, start over with the recap. Paste your summary as the first message of a new chat. You lose the old transcript, but you keep the story, and the character comes back sharper than it was.

What each app gives you

• Character.AI does not say how big its window is. It gives you pinned messages, a memory box of 400 characters, and a Story Memory that collects facts on its own, with more of each on paid plans. Pinned messages take space from the same window.
• JanitorAI says its window holds about 8,000 to 9,000 tokens on its own model. It gives you a Chat Memory field, with the advice "list facts, not scenes", and recommends keeping the card under 1,500 tokens.
• Chai says nothing about memory. Users report that a character is limited to 625 characters of text.
• SpicyChat gives you 4,096, 8,192, or 32,768 tokens depending on your plan, plus a memory manager on paid plans.
• SillyTavern draws a dotted line in the chat to show where the window ends. Its tools are the Summarize extension, the Author's Note, and World Info entries.
• With your own API key, you set the window size yourself. Around 16,000 to 32,000 tokens works better than the model's maximum, and most providers charge much less for the part of the prompt they have already seen. The API-key guide has the prices.

Some apps advertise unlimited memory. They have the same limit as everyone else. What they have is a way of deciding which old messages to keep and which to drop. The honest ones explain how they decide.

Related guides: How to write a character card that works · Which API key you need for AI roleplay · all guides.

Sources

• OpenAI: conversation state and Anthropic: context windows: every request starts from zero, oldest messages dropped first, long windows degrade
• Gemini API: tokens: about four characters per token; Chroma: Context Rot: long inputs degrade recall across 18 models
• Character.AI: Story Memory and Facts and the memory box
• JanitorAI: tokens, chat memory, proxy context size
• Chai: FAQ (silent on memory); r/ChaiApp on the 625-character limit (user reports)
• SpicyChat: tokens and context; SillyTavern: context settings, Summarize, World Info
• User reports: the "overwriting" theory, how chat apps handle memory

Character.AI, JanitorAI, Chai, SpicyChat, SillyTavern, OpenAI, Anthropic, and Google are independent products of their respective owners. LonelyTavern is not affiliated with or endorsed by any of them. Limits and statements were read from their pages on September 18, 2026 and may have changed since.