Devices, systems, and methods are provided for adherence monitoring, and devices, systems, and methods are provided for monitoring use of consumable dispensers. In general, the devices, systems, and methods can facilitate an individual's adherence to a schedule for consuming consumables and can facilitate monitoring and tracking of the individual's adherence to the schedule. The devices, systems, and methods can allow data regarding the individual's historical adherence to the schedule to be accessible via a computer system. In one embodiment, an accessory is provided that can be configured to attach to consumable dispensers. The accessory can be configured to be removably and replaceably coupled to the dispenser. The accessory can be configured to provide a notification to a user indicating that a certain event occurred and/or that a certain action needs to be taken. The accessory can be configured to sense attachment thereof to and removal thereof from the dispenser.