Not very convenient but I have a way to enjoy apps without recharging DTH, Go to settings ---> apps ---> Airtel Xstream ---> Force Stop
Now, press back button and move back to apps list -----> Look for play store and open from the settings, to your surprise play store will open.
Now, search and install ATV Launcher (Or any launcher of your choice) -----> Open ATV Launcher from app store
Voila you can see all apps there and they would open normally.
Actually the check is done by their Launcher so if we could root and delete that launcher and install android tv home ( Google launcher for android Tv), then theoretically that would bypass the subscription check also.
Unfortunately, you have to force stop Airtel Xstream every time till then. Also I would recommend not to upgrade your box as they may fix this vulnerability and use some other method to check for subscription. Till then enjoy!