Ads and Paid User Acquisition
The period of time between when a user sees or clicks an ad and takes an action to download an app (or some other action, like going to a website, purchasing a subscription, etc.).
ASA measures attribution for up to 30 days. Facebook offers 1, 7, and 28-days attribution. The data about conversion and ad effectiveness can differ from different sources, mostly because of re-download data, LAT, and API glitch.