The AppsFlyer platform attributes any revenue event to the install source, regardless of how much time has passed since the initial install occurred. Our default retargeting (re-engagement) attribution window (for revenue events) is 30 days, and this is fully configurable (as desired).
Consider the following illustration:

In this case, credit will be attributed to the re-engagement campaign (after the user clicks and opens the app). When it comes to LTV calculation, there is a clear distinction between UA and re-engagement, based on the following:

To prevent duplication, marketers can simply mark any events that occur within the re-engagement window as ‘Primary’ to enable deduplication.