The unique visitor concept aims to identify and quantify every individual who accesses a website, even if they visit the site multiple times in the same time period.
The short name quota applies to every time a user changes the short name of a link that has previously been changed (not including changing from a generated name to a custom name). The quota will be available again after the date of resetting the quota or upgrading to a higher service.
now you can change the destination address or original link from your shortlink. This only applies to Starter services with 3 quotas changes per month.