The idea is that you can sub all the previous months you missed since you first followed the streamer which can support the streamer further. Example is if you followed someone for 2 years and you subbed for 10 months you can sub for the previous 14 months with a selection on Tier 1, 2, or 3. and you can only sub from the follow date and no further. The subs from the past feature does not add to any current streaks if you subbed at 10 months onwards it will stay at 10 and say the total months subbed which would be the date you followed to the current month adding onto what you have already subbed. The alert message would say (user) has used a time machine and subbed from the past and will show the amount of months subbed with the streak as usual. Just an idea to help streamers get a little more support.