# Updating environment variables

[Environment variables](https://docs.uibakery.io/on-premise/environment-variables) are a crucial part of configuring your UI Bakery On-Premise installation. They can control various settings, including your [license key](https://docs.uibakery.io/on-premise/install-and-update/updating-license-key), [database connections](https://docs.uibakery.io/on-premise/install-and-update/recommendations/running-a-standalone-database-instance), [domain name](https://docs.uibakery.io/on-premise/networking-and-security/setting-up-a-domain-name) and application behavior. Here's how you can modify them.

After the installation of UI Bakery On-Premise, a directory named `ui-bakery-on-premise` is created. Within this directory, you will find a file named `.env`. This file contains the [environment variables](https://docs.uibakery.io/on-premise/environment-variables) for your instance.

To modify any variable, such as your license key or other settings:

1. Open the `.env` file using a text editor. You can do this through the command line or by navigating through the file explorer to `ui-bakery-on-premise` and opening the `.env` file.
2. Find and modify or add a new variable:
3. ```bash
   UI_BAKERY_LICENSE_KEY=new_license_key_value
   ```

   Make sure to save the file after making your changes.
4. To apply the changes, a system restart is necessary. Accomplish this by running the following commands in your terminal:

   ```sh
   docker compose down
   docker compose up -d
   ```

{% hint style="info" %}
Restarting your UI Bakery On-Premise instance with `docker compose down` and `docker compose up -d` does not erase your data. Persistent data is stored in Docker volumes, ensuring it remains safe across container restarts.
{% endhint %}