You can make it work with cloudflare, just a bit configuration needed so CF is sending you the real visitor IPs, otherwise every hit looks like it's done by distributed CF machines.
When not using a cookie, the plugin will look at the `document.referrer` value to determine whether a visitor is returning and whether a pageview is unique (less reliable, but should be good enough for some).
IP addresses are not looked at at all (let alone stored).