What is the lifetime of the sensor and when do we need to replace them.
How often to clean and replace the sensor filter cap.
ANSWER: Cleaning and replacement is very dependent on application and contamination. Please let us know how you plan on using the sensor and we can be more specific. If you use it in clean indoor conditions, you will most likely never have to replace the filter but a calibration check once a year is recommended since indoor VOC's may affect long-term accuracy.
The best way to determine the recalibration interval is to perform a calibration check after a year on one sensor and decide whether it is still within specifications in your environment. This will guide you in your decision when to recalibrate your other sensors which are in a similar environmental.
A practical approach like this is the only sure way to determine recalibration/replacement intervals of all humidity sensors. Many temperature sensors do not have this problem but their long-term drift should be validated using the above approach.