Your specific question has been answered. PaperUI is being replaced in OH 3 and the Expire binding is not supported in OH 3. However, I believe they are working on some new sort of scheduler which might be a suitable replacement for Expire 1.x.
If not or until it becomes available, I created Jython Drop-in Replacement for Expire 1.x Binding (requires setup and use of Jython rules). I am pretty certain that the replacement for PaperUI allows the configuration of metadata on Items so you can configure everything through the new UI.