Why am I seeing conversions on my creatives but no clicks or impressions?

This article discusses why you're seeing conversions by not clicks or impressions on your creatives.

Once an advertisement flight has ended, you will no longer be getting clicks or impressions. However, due to the view-thru and click-thru attribution window, conversions can still populate after the flight has ended. Conversions are recorded up to 90 days after an impression is served, therefore, conversions can be tracked for up to 90 days after a campaign ends.