Are there any fees to use the Lutron app?

Caséta, RA2 Select, and RadioRA 3 

Caséta, RA2 Select, and RadioRA 3 do not require a subscription to use the Lutron app.

RadioRA2 and HomeWorks QS

If the customer did not have Alarm.com, they would have to buy a one-year subscription in order to use RadioRA2 and HomeWorks QS with the Lutron app. This is an annual charge to the customer in order for them to be able to remotely control their devices.

Since the customer is using Alarm.com, they can integrate Lutron with the Alarm.com app and do not need to use the Lutron app at all.