The Depreciate was last run field is standard. You can enter it manually or it fills in automatically after depreciation runs.
The Depreciate until field on the Fixed asset page relates to the business object. Both fields must match to scrap the fixed asset or convert the rental object to inventory.
Finance specialists use this field to validate the fixed asset. It helps confirm whether the business object is still on rent. You must manually update the last on-rent date. This ensures proper validation before the object is converted or written down.