# Remember a Fact in Durable Agent Memory

> Remember a Fact in Durable Agent Memory is a paid API for AI agents from memory.withzero.xyz, paid per call via MPP, metered — billed by usage, status unknown (last checked 2026-09-14).

Stores a text memory (fact, context, or standing order) into durable, private agent memory with optional namespace, key, tags, and pinning.

## Facts

- Endpoint: POST https://memory.withzero.xyz/api/v1/memories
- Price: metered — billed by usage
- Payment: MPP
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 3
- Provider: memory.withzero.xyz
- Website: https://memory.withzero.xyz
- Canonical page: https://www.zero.xyz/c/memory-withzero-xyz-remember-a-fact-in-durable-agent-memory-dcb7cbae
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_IURuGB15VPKte6W8Q1urV

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability memory-withzero-xyz-remember-a-fact-in-durable-agent-memory-dcb7cbae -d '<json body>'
```

Example prompt: Remember this for me durably: 'The user prefers concise responses and always wants output in bullet points.' Pin it as a standing order under namespace 'agent:preferences' with key 'response-style' and tag it as 'formatting'.

## When to prefer this

Use this endpoint when you need to persist a fact, preference, instruction, or context durably across agent sessions, especially when you want namespaced organization, tagging for later recall, or pinned 'standing orders' that always surface during recall. Prefer this over in-context storage when information must survive beyond the current conversation or be retrievable by a separate recall query.

## Known failure modes

- Missing required 'content' field returns a 400 validation error
- Content exceeding 8192 characters is rejected
- Key collisions under the same (owner, ns) pair may overwrite or error
- Insufficient prepaid balance may block the write
- Namespace or key strings exceeding length limits are rejected
- More than 32 tags supplied returns a validation error

## How this service works

Remember a fact or context in durable agent memory.

## Output

Returns the memory's assigned ID, the key (caller-supplied or auto-generated), and the remaining prepaid USDC balance in micros after the write operation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "content"
 ],
 "properties": {
  "ns": {
   "type": "string",
   "maxLength": 128,
   "minLength": 1,
   "description": "Namespace under the caller (e.g. agent:coder). Defaults to \"default\"."
  },
  "key": {
   "type": "string",
   "maxLength": 256,
   "minLength": 1,
   "description": "Caller-chosen key, unique per (owner, ns). Omit to auto-generate."
  },
  "tags": {
   "type": "array",
   "items": {
    "type": "string"
   },
   "maxItems": 32,
   "description": "Optional tags for later filtering."
  },
  "pinned": {
   "type": "boolean",
   "description": "Mark as a \"standing order\": always surfaced by recall and never consolidated/suppressed by dreaming. Omit on update to leave it unchanged."
  },
  "content": {
   "type": "string",
   "maxLength": 8192,
   "minLength": 1,
   "description": "The memory text to remember."
  }
 },
 "additionalProperties": false
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "id",
  "key",
  "billing_rail",
  "replayed",
  "balance_micros"
 ],
 "properties": {
  "id": {
   "type": "string"
  },
  "key": {
   "type": "string"
  },
  "replayed": {
   "type": "boolean"
  },
  "billing_rail": {
   "enum": [
    "direct",
    "zeroclick"
   ],
   "type": "string"
  },
  "balance_micros": {
   "type": "string",
   "description": "Remaining refundable direct-rail prepaid balance in USDC micros. ZeroClick usage never changes it."
  }
 },
 "additionalProperties": false
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/memory-withzero-xyz-remember-a-fact-in-durable-agent-memory-dcb7cbae/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from memory.withzero.xyz](https://www.zero.xyz/host/memory.withzero.xyz/llms.txt)