---
title: "Mem0MemoryStore"
id: mem0memorystore
slug: "/mem0memorystore"
description: "A memory store backed by the Mem0 cloud API."
---

# Mem0MemoryStore

`Mem0MemoryStore` is a memory store backed by the Mem0 cloud API. It is the shared data layer used by [`Mem0MemoryRetriever`](../pipeline-components/retrievers/mem0memoryretriever.mdx), [`Mem0MemoryWriter`](../pipeline-components/writers/mem0memorywriter.mdx), and the [Mem0 Memory Tools](../tools/ready-made-tools/mem0memorytools.mdx).

<div className="key-value-table">

|  |  |
| --- | --- |
| **Used by** | [`Mem0MemoryRetriever`](../pipeline-components/retrievers/mem0memoryretriever.mdx), [`Mem0MemoryWriter`](../pipeline-components/writers/mem0memorywriter.mdx), [`Mem0MemoryRetrieverTool`, `Mem0MemoryWriterTool`](../tools/ready-made-tools/mem0memorytools.mdx) |
| **Optional init variables** | `api_key`: Defaults to `MEM0_API_KEY` environment variable |
| **API reference** | [Mem0](/reference/integrations-mem0#mem0memorystore) |
| **GitHub link** | https://github.com/deepset-ai/haystack-core-integrations/tree/main/integrations/mem0 |
| **Package name** | `mem0-haystack` |

</div>

## Overview

`Mem0MemoryStore` wraps the Mem0 cloud API and provides two core methods:

- `add_memories` — stores a list of `ChatMessage` objects as memories in Mem0.
- `search_memories` — retrieves memories from Mem0 that are relevant to a query.

Scope memories with at least one Mem0 entity ID: `user_id`, `run_id`, `agent_id`, or `app_id`. These are runtime parameters, so a single store instance can serve multiple users or sessions.

The `infer` parameter on `add_memories` controls how Mem0 processes incoming messages:

- `infer=True` lets Mem0 extract memories from the messages automatically. This is useful when storing a full Agent turn.
- `infer=False` stores the supplied message text as-is. This is useful when the exact memory text has already been selected upstream.

### Installation

Install the Mem0 integration:

```bash
pip install mem0-haystack
```

Set your Mem0 API key:

```bash
export MEM0_API_KEY="your-mem0-api-key"
```

## Usage

### On its own

```python
from haystack.dataclasses import ChatMessage
from haystack_integrations.memory_stores.mem0 import Mem0MemoryStore

store = Mem0MemoryStore()

store.add_memories(
    messages=[ChatMessage.from_user("Alice prefers concise Python examples.")],
    user_id="alice",
    infer=False,
)

memories = store.search_memories(
    query="What does Alice prefer?",
    user_id="alice",
    top_k=3,
)
print([msg.text for msg in memories])
```

### Scoping with multiple entity IDs

Mem0 supports narrowing the scope of reads and writes with `user_id`, `run_id`, `agent_id`, and `app_id`. Pass any combination at call time:

```python
store.add_memories(
    messages=[ChatMessage.from_user("Alice is working on a documentation search system.")],
    user_id="alice",
    run_id="docs-assistant-session-1",
    infer=True,
)

memories = store.search_memories(
    query="What project is Alice working on?",
    user_id="alice",
    run_id="docs-assistant-session-1",
)
print([msg.text for msg in memories])
```

### Retrieving all memories in scope

Pass `query=None` to return all memories matching the provided scope without a relevance search:

```python
all_memories = store.search_memories(query=None, user_id="alice")
print([msg.text for msg in all_memories])
```