Hi Josh,
GoodData Cloud authentication works with OAuth 2.0 and OIDC standard. When logging into GoodData, authentication flow is triggered with your IdP (Google) according to the standard, at the end of the flow, access token, id token and possibly refresh token is obtained, encrypted and stored in browser cookies creating a login session. As long as the access token or refresh token are valid a user stays logged in. Access token is usually short-lived and grants access to the application. Refresh token is usually long-lived and is used to issue a new access token when it expires (it is automatic and seamless to the user). There is no setting to alter login session on GoodData Cloud. Login session should be managed by your IdP. I’m not that familiar with Google as IdP but I would suggest you to check what is the validity period for the tokens and if there is an expiration set.