---
title: "Register the application with Adyen"
url: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/com-extension-for-windows-integration/key-steps-com-extension/register-the-application-with-adyen-com-extension"
source_url: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/com-extension-for-windows-integration/key-steps-com-extension/register-the-application-with-adyen-com-extension.md"
canonical: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/com-extension-for-windows-integration/key-steps-com-extension/register-the-application-with-adyen-com-extension"
last_modified: "2026-05-23T12:56:20+02:00"
language: "en"
---

# Register the application with Adyen

[View source](/point-of-sale/classic-library-deprecation/classic-library-integrations/com-extension-for-windows-integration/key-steps-com-extension/register-the-application-with-adyen-com-extension.md)

After you initialize the library, you must register the cash register application with Adyen.

## POS Object

| Name  | Description                                               |
| ----- | --------------------------------------------------------- |
| `POS` | POS object that represents the cash register application. |

## Method

| Name          | Description                                                                                                                                                                                                  |
| ------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `RegisterApp` | Registers the cash register application with Adyen. Registration requires a valid merchant account and API credentials to access the Adyen payments platform. A unique cash register identifier is required. |

## Parameters

| Name              | Type   | Required                                                                                    | Description                                                                                                                                                                                                                                                        |
| ----------------- | ------ | ------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `merchantAccount` | String | ![-white\_check\_mark-](/user/data/smileys/emoji/white_check_mark.png "-white_check_mark-") | The merchant account used for registration.                                                                                                                                                                                                                        |
| `wsUser`          | String | ![-white\_check\_mark-](/user/data/smileys/emoji/white_check_mark.png "-white_check_mark-") | Username of your API credential. In the Adyen Customer Area, go to **Developers** > **API credentials** to create a new credential. For more information, see [API credentials](/development-resources/api-credentials).                                           |
| `password`        | String | ![-white\_check\_mark-](/user/data/smileys/emoji/white_check_mark.png "-white_check_mark-") | Basic authentication password for the API credential. In the Adyen Customer Area, go to **Developers** > **API credentials** to add a new password. For more information, see [Basic authentication](/development-resources/api-credentials#basic-authentication). |
| `appID`           | String | ![-white\_check\_mark-](/user/data/smileys/emoji/white_check_mark.png "-white_check_mark-") | Unique ID of the cash register application.                                                                                                                                                                                                                        |

Register the application once, after the cash register starts.

## Callback

| Name            | Description                                                                          |
| --------------- | ------------------------------------------------------------------------------------ |
| `RegisterAppCB` | The Register App Callback returns the result of registration, as well as any errors. |

## Parameters

| Name           | Type                                                                                                                                                               | Description                                                                                                        |
| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------ |
| `appObj`       | [AppInfo](/point-of-sale/classic-library-deprecation/classic-library-integrations/com-extension-for-windows-integration/com-extension-for-windows-objects/appinfo) | Object that holds POS information. The Adyen payments platform uses this information for application registration. |
| `pedResult`    | int                                                                                                                                                                | Result denoting whether an error occurred on the PED. A value of 0 means no error occurred.                        |
| `pspResult`    | int                                                                                                                                                                | Result denoting whether an error occurred on the PSP. A value of 0 means no error occurred.                        |
| `libResult`    | int                                                                                                                                                                | Result denoting whether an error occurred in the Library. A value of 0 means no error occurred.                    |
| `errorMessage` | String                                                                                                                                                             | Error message describing what went wrong.                                                                          |