Stop non used kernels: when you are done with a Jupyter notebook, make sure you stop the kernel to take full advantage of available resources. To do so, navigate to Running terminals and kernels on the top left sidebar and shut down the chosen notebook.Log-out: once you finished working on your JupyterLab environment, save your changes (either by downloading or pushing to your personal git repository) then go to File on the top left of the main menu and click Log out. An auto-logout period otherwise be applied and you could loose your work.
Token regeneration: access to Ganymede is granted through an authentication token with a limited lifetime. When running a notebook and an error "Unauthenticated" raises, please make sure your Log out and re-login. To check your token validity, refer to this link and copy/paste your token, which is generated in the Step 2 of every Jupyter notebooks.