Websites - including the Origin Creator - sometimes store more permanent data in a place called localStorage.
localStorage is a database on your own computer, managed by your browser, that stores up to 5MB of data per website you visit.
For server-side applications, data is usually stored on a server somewhere; however, for static sites without a specific server (like this one), permanent data can only be stored locally, and this is done in localStorage. These sites are usually pretty small, since they are limited to 5MB each.
Unfortunately, Google Chrome, and most Chrome based browsers, are hardcoded to the 5MB limit.
Firefox, and some other browsers, let you reconfigure it to be larger or smaller. Go to about:config and search for the dom.storage.default_quota option. It's value is in kilobytes.