Starting November 30, 2022, HubSpot API keys will no longer be able to be used as an authentication method to access HubSpot APIs. Instead, you need to set up HubSpot's private app to make the integration between HubSpot and the billing.

Creating a private app

Go to HubSpot > Settings > Integrations > Private Apps > Create a private app.

You can give an app any name and description.

In the Scopes section, you will need to add specific permissions for the app so that billing can access and modify HubSpot contacts.

- Enter contact in the search field and allow crm.objects.contacts both read and write permissions.

- Also enter owner in the search field and allow crm.objects.owners read permission.

After that you can Create app

Private app's access token

After creating a private app, you will need to copy its access token and paste it into the billing to activate the integration.