Thank you for your questions and feedback!
WifiMask uses OpenVPN for the macOS app and IKEv2/IPSec for iOS. We haven't had 3rd party audits yet, this is definitely on our wish list, because we understand it's all about trust. Alternative payments like bitcoin are on the list as well, we aim for total anonymity for our users, payments are part of that. To be honest we can't track any illegal activity, because we have a strict no log policy, all we can do now is say it is not allowed. We have nothing to hand over to enforcement either, they have to find different ways of getting the information they want. We should investigate and think about transparency reports and a public disclosure policy too, thanks!