Additional expiration by years

Issue Summary

Would it be possible to have a user select, for example, "three years after last update" as the time of expiration? Can this do multiple years? Thanks for the support or an added feature that would allow this. In my case, I have a site with county departments that update their forms every three years, and also an assessment site that I want to be able to republish a node after five years. This would be a wonderful feature. Thank you for the great module.