Problem with pay app

[dimipap]

Hello
My phone is Huawei p40 pro.
I have downloaded the app from aurura.
My problem is that I can't pay for the app.
The error message that makes me is
Billing error:
Billing service unavailable on device.

How can I pay the app to work sstp vpn?
Thanks

[admin]

This happens because the device doesn't have the Google Play and/or Google Services app.
Premium features can only be bought and used on devices that have the Google Play app