You, the landlord are required to give all tenants listed on the agreement copies (keep original keys yourself) of keys for the entire premises. This includes swipe cards or remote controls for all lock opening devices i.e. garage, doors, windows, or letterboxes.
The Tenant is responsible for returning all copies of property keys given to them by you at the start of the tenancy.
A tenant may be charged for rent up until the keys are returned, or the cost of changing the locks.
You cannot charge your tenants any seperate fee or deposit for keys, but you may charge for the actual cost of replacing any keys.