Some changes are being case to warn users about notebooks which haven't been accessed in some time (3 weeks) and automatically suspend them given a further grace period. The reason for this and the explanation of how it works can be found here https://datalab-docs.datalabs.ceh.ac.uk/howto/suspend-and-restart-resources/. An example warning will be shown for a week before the notebook is suspended as seen below. Note that once suspended a notebook can easily be restarted with no data/configuration loss so this should have minimal impact.
Please don't hesitate to get in touch with us if you're unsure about how this works or have a special requirement for your project.