How AI Companion Memory Actually Works

Short-term vs long-term memory

Short-term memory is the rolling context window — usually the last 20–100 messages the model can see directly.

Long-term memory is a separate database (typically a vector store) where facts about you and the relationship are saved and retrieved on demand.

Why companions forget

Two reasons: the rolling window pushed an important detail out, or the long-term memory layer never wrote it down. Better platforms run a background summarizer that promotes important facts into long-term storage automatically.