Keyholders are responsible for locking up the space when leaving.
The dooraccess page in Nomos has detailed instructions for keyholders on how to lock up the space when leaving.
Checklists have been shown to improve consistency and completeness when completing safety-critical tasks. There is a mobile-friendly lockup checklist accessible at lockup.vanhack.ca complete which checkboxes and a little banner that tells you when you're done. This is completely client side i.e. it's not audited or saved anywhere. It exists because physically checking off boxes has been shown to be more effective than just mentally running through a list of things to do or reading some dotpoints on a page and nodding along.
The code for lockup.vanhack.ca is in the vhs/lockup-checklist repo on GitHub. Changes should be synced every 1-2 minutes.