3.0.0
From now Qonversion supports Google Play Billing Library 4.0.0.
If you are using Qonversion Unity SDK in Observer Mode, please check the Google Play Billing Library version in your in-app subscription implementation. For the library version 3.x.y, you have to use the major version of the SDK 2.x.y. In other cases use the latest SDK version (version 3.0.0 and above).