I'm making progress on IndieAuth for ProcessWire and currently thinking about access token expiration. I am thinking about including a setting for token expiration time so people can set that (default: two weeks).
Occasionally you may want to give an app non-expiring access, though. Below is a screenshot of the interface I've been working on for that. It's definitely an alpha version, but any feedback would be appreciated, especially on user-friendliness.