Hi Alex,
The free Metered World you get with a Regular Kitely account is:
1) Given to you without you needing to pay Kitely anything or even so much as give us your billing information.
2) Accessible to you for free for up to 6 hours.
3) Remains accessible to anyone on a Premium account indefinitely without it costing you anything.
In other words, you might not be able to access it for more than 6 hours for free but many other people will be able to access it without it costing them or you anything extra. The majority of Kitely worlds are set up this way and many of them are occasionally visited by Premium account users despite the fact the the person who created those world(s) never paid us anything.
Some of those worlds hold galleries, others hold information centers, some are sandboxes, others are advertisements for people's virtual world businesses (in or outside Kitely) and some offer some entertainment value. In any case, all those worlds are maintained free of charge to the people who created them and offer enough value to them to not want to delete them (which they can easily do at any time by pressing a Delete link in their My Worlds page).
You might not see value in those things but many people do, many also like knowing they have a world available to them if they ever want to visit it and buy Kitely Credits in order to be able to do so. Their worlds remains available for them and others without them needing to pay Kitely for maintaining it active or having to periodically "activate" that world so it won't be deleted. There is value to the customer and that value was given by Kitely without Kitely charging the customer - that would be labeled as Free by most definitions I know.