There's no way of proving a VPN provider is not logging[0]

Also worth reading this guide which is much more comprehensive than that TorrentFreak article:

https://thatoneprivacysite.net/vpn-comparison-chart/

[0] https://gist.github.com/joepie91/5a9909939e6ce7d09e29

[#] http://blog.hidemyass.com/2011/09/23/lulzsec-fiasco/