The Warp Stool is a device that will take you to a tier meter map for the region you're in. Whenever you purchase land the tier meter will give one of these to you.
If you need to pay your tier for a parcel you're the owner of, simply rez this object in the region that the parcel is in and then sit on it. It will take you to the tier meter map.
If you've lost your Warp Stool and need a new one simply IM NeoBokrug Elytis, and you will get a new one.