A service account is an administrator account, especially for API integrations. This account does not require a password nor can you log-in with this account. A service account is to connect your organization Drillster environment with your LMS and it behaves like an administrator.

The service account has to be granted the permissions same as an administrator in order to take actions via API. 

You can create this account via 'accounts'. 

Are you looking for the technical documentation about the service accounts, click then here.