First, all session information is held in RAM. Bandwidth and traffic are used on the Status page.
IP addresses are inevitably known and displayed on several webpages across airvpn.org for transparency.
Traffic and timestamps are saved in your Archive. This is enabled by default but can be disabled, doing so will clear the archive. I think Air has no access to it.
DNS queries are not saved at all.
And you don't need official responses for recurring questions. There are users whose answers are more than satisfactory in that regard. Still, if you don't trust the regular long-time user and demand proof, Question regarding AirVPN's "Your IP" has some of the answers I gave you "black on white".