# Expire After a Duration

In this guide, you'll learn how you can configure a Grant Kit to automatically revoke access to a grant after some duration. You'll do this by importing and using an expiration policy Abbey provides out-of-the-box.

We will be using the [Quickstart](/getting-started/quickstart.md) as a base and modify it to this use case.

## Step 1: Add a Directory for Your Policy

In your repo, add a directory to put your policies.

{% code title="/" %}

```diff
.github/
+ policies/
+   .manifest
+   common.rego
.gitignore
.terraform.lock.hcl
LICENSE
README.md
access.tf
main.tf
outputs.tf
variables.tf
```

{% endcode %}

{% hint style="info" %}
Abbey will automatically build your policies for you using the standard Open Policy Agent (OPA) CLI via `opa build`.
{% endhint %}

## Step 2: Configure Your Manifest and Policy

First, configure your Manifest in your `.manifest` file. This will tell the Policy Engine where your policy file is located.

```diff
+ {"roots": ["common"]}
```

Next, write your policy using Abbey's expiration helper functions.

{% code title="common.rego" lineNumbers="true" %}

```rego
package common

import data.abbey.functions

allow[msg] {
  functions.expire_after("24h")
  msg := "granting access for 24 hours."
}
```

{% endcode %}

{% hint style="info" %}
Abbey revokes grants in realtime. When 24 hours has passed, the grant will be revoked immediately.
{% endhint %}

{% hint style="success" %}
Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
{% endhint %}

## Step 3: Add Your Policy

Now that you have your policy set up, you can add it to your Grant Kit.

{% code title="main.tf" lineNumbers="true" %}

```diff
resource "abbey_grant_kit" "null_grant" {
  ...
  
+  policies = [
+    {
+      bundle = "github://example-org/example-repo/policies"
+    }
+  ]

  ...
}
```

{% endcode %}


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.abbey.io/use-cases/time-based-access/expire-after-a-duration.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.