My initial answer is, “Until you finish the last piece! ” Which, for most people isn’t very long. 🙂
But, if you want to know storage times, please use the following:
On the counter: ~1 week
In the refrigerator: ~4 weeks
In the freezer: pretty much as long as you want. 🙂 However, when thawing, please set it out on the counter and let it thaw naturally at room temperature. I highly discourage using the microwave, it actually changes the bread.