Well, okay - which part doesn't sound low cost - when compared to adding Tx, ADS-B etc. that others suggest? if its the telemetry data feedback that you think might be the costly part, well certainly with DJI, that already exists and is logged for every flight made - I know this only because I have two drones from aforementioned manufacturer (Mavic and Inspire 2), and both log Lat/Long, Altitude, Distance etc., etc. already (heck, even plots route flown on to Google Maps also as a plan view track breadcrumb!).
The updating requirement monthly would not be onerous upon a manufacturer, as firmware requires updating almost monthly anyway - make the drone a 'no fly' model if firmware isn't updated (can be easily done via the drone firmware) by adding a server timestamp limit/restriction or such like, and this then mandates people need to communicate with the manufacturer of said drone to enable flight.
If I'm missing the cost element here by comparison, standing by to be enlightened
