To make the purchase, you must associate a credit card or a prepaid card to your Google Play (or Huawei AppGallery) account.

Unfortunately, the Stores do not manage purchases in all countries.
Check if your country is supported:

Google Play paid app availability

Huawei AppGallery paid app availability

To restore the subscription on the new device you must be logged in to the Store with the same account (email address) used for the purchase.
Finally, go to the app settings and select the “Restore purchase” option.

It is not possible to restore a purchase made with another account or using a different Store.

No, you can’t transfer the license.
The app is distributed by two different Stores: PlayStore for Android and iTunes for iOS.
In this case you must purchase a new license.