The plugin doesn't use IP addresses at all, so this isn't needed. There is an option to determine returning visitors using a cookie (easiest, realiable) but it

The plugin doesn't use IP addresses at all, so this isn't needed. There is an option to determine returning visitors using a cookie (easiest, realiable) but it can be turned off. 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).