Google Play Billing Library 2.0: must old non-consumable purchases be acknowledged?

Question

I'm currently in the process of switching existing apps from Play Billing Library v1.x to v2.0.

For in-app purchases that are not consumables (one-time purchase that unlocks premium features for example), how does this work for purchases made before Google introduced acknowledgements and before the app used Play Billing Library v2.0?

Can they be acknowledged? Must they be acknowledged? If they must be acknowledged, I suppose there's no "3 days" limit?

Answer 1

According to pencoba on GitHub, he made this test:

I've tried an experiment. First I bought an IAP using AIDL (without acknowledgement) then using Play Billing 2.0.0 I checked if it's acknowledged, the result is it is acknowledged.

Confirme then by someone from Google:

Purchases using AIDL directly or a billing library < 2.0.0 will not need to be acknowledged by your application. When you query these purchases via our server APIs or through billing library 2.0.0 they will be marked as acknowledged. I will work on clarifying this in our documentation.

https://github.com/googlesamples/android-play-billing/issues/198