Is there a session like variable for logged in user?

In my application i have a thin client, which communicates with kanboard through a server application.
I would like to authenticate once, and after that work with a session if possible

According to the documentation (https://docs.kanboard.org/en/latest/api/me_procedures.html), the getme method returns a user session, but there is no variable in the response data that looks like a sessionid.
Is the user apikey meant for that, or i am missing something?

Thanks in advance

$this->userSession->getId()