I have some questions about aging a starter

I mainly want to see how long I can keep my starter going before I call it a wrap, but I actually want to try to keep her long term.

I went off of King Arthur’s instructions for making a starter.

Just curious on if it continues to have activity on its own (in other words, its own produced yeast is active), do I need to add WW flour in once in a while? Probably not. I’m not sure how it looks to age a starter out