Unfortunately, it's impossible to transfer the subscription from iOS to Android or vice versa. On iOS, subscription is connected to your Apple ID. On Android, it's connected to your Google Play account or HUAWEI ID (depending on the store which you got the app from). These are different platforms and different accounts.

Please note that if you bought the subscription in the Play Store, you will be able to use it only on an Android device with Google Play services. But if you have another Android device without Google Play services and if you download the app in the AppGallery, you will need to buy a separate subscription.