How long will the starter last after the first dreaded clicking and no crank up?

I do not know how to “push start” no, it is a manual though. I skipped changing the battery because all the interior lights work, just the engine wouldn’t crank first try, and is progressively getting worse. If it happens to be the battery, I will be estatic to get the refund for the expensive starter and use a quarter of it for a battery replacement.