# API Key

> Key concepts for API Key usage in Document Understanding, including how AI Units entitlement controls access to machine learning model endpoints.

The **AI Units** section in the **Consumables** tab on the **Licenses** page displays the consumption entitlement (AI Units) that can be extracted by our Machine Learning servers based on your AI Units entitlement.

![Animation on how to navigate to the Lincenses page.](https://dev-assets.cms.uipath.com/assets/images/document-understanding/latest-animation-of-the-api-key-field-in-the-admin-page-334966-b2df9e44-bb2075cf.gif)

Access to the models' endpoints is granted based on an API Key. The API Key is generated automatically when you create your account, and it is required for the following activities in Studio:

* Form Extractor
* Intelligent Keyword Classifier

These activities allow you to use UiPath® ML models.

Select **Copy API Key** to copy the displayed API Key to your clipboard and then paste it in your activity or in the case of UiPath® OCR, in the UiPath Document OCR engine activity.

A request is sent from the activity to the Machine Learning Server, and access is granted based on your API Key.

If at any point the API Key is compromised, discard it by generating a new one.

Keep in mind that we limit the size of documents that can be processed by our servers. For more information, check the [Known limitations](https://docs.uipath.com/document-understanding/automation-cloud/latest/user-guide/known-limitations#known-limitations) page.

:::note
Machine Learning technology is probabilistic in nature. UiPath makes continuous efforts to improve our Document Understanding products but can not guarantee accuracy or performance on any particular business document.
:::