API account and license requirements

Working with a client that is creating an API to integrate our Jira Service Desk Cloud instance to their ServiceNow instance. The integration requires bidirectional updating.

So, the questions are:

  1. Do I need to make an account for the integration, or is there some backend way to accomplish the communication without an account?
  2. If the integration needs an account, can it be a Customer account or must it be a regular Jira Service Desk account?
  3. If it must be a regular Jira Service Desk account, is there a way to get an @connect.atlassian.com account so it doesn’t consume one of our licenses?