Android Hack by Kali Linux & NGROK - Facing issues

I have tried a lot of times from different tutorials from Youtube to interface kali Linux with ngrok & fatrat but could not succeed.

I have question that ngrok has only limited session for a single ngrok IP and after that session, the injected ratware(fatrat) in Android will be useless as ngrok session IP will change.

Does it mean we need to buy ngrok to continuously monitor an android phone for a long? Or there is other ways?

What about monitoring multiple android phones by fatrat & ngrok.? Can this be done with ngrok premium?

Ngrok is not working since March 2020 I didn’t figure out the reason yet but this is just not working in kali linux anymore…Maybe they restricted their services…

Thanks. What about portmap.ip??