"Then, if that user eventually signs up during a later visit, KISSmetrics will associate their previously anonymous profile with their email address or user nam

"Then, if that user eventually signs up during a later visit, KISSmetrics will associate their previously anonymous profile with their email address or user name. Which means that site admins can look at both how a user is currently using their site, and how they used it months or years before they actually created an account"