Out of the box, ColdFusion stores client variables in the server’s Registry and will delete all client variables for any visitors who don’t return to your site for 90 or more days. You can, of course, tweak these behaviors to suit your needs. This section discusses the client-variable storage options available.
Normally, client variables are maintained on what amounts to a permanent basis for users who visit your site at least once every 90 days. If a user actually lets 90 days pass without visiting your site (for shame!), all of their client variables are purged by ColdFusion. This helps keep the client-variable store from becoming ridiculously large.