Token expiration time


I created an application in GitLab and use it to get access and refresh token. I use the way GitLab as an OAuth2 provider | GitLab

According to the documentation, expires_in should come to me:

But in fact I don’t get expires_in:

    "access_token": <access_token>,
    "token_type": "Bearer",
    "refresh_token": <refresh_token>,
    "scope": "api",
    "created_at": 1626351223

How can I find out how long an access_token is kept and also how long a refresh_token is kept?

And also, if the method when updating the access_token using refresh_token does not generate a new refresh_token?

Thank you!