It can last quite a while, but the thing I do with my dehydrated foods is vacuum seal and freeze, gives me that reassurance and I’m not dehydrating for preservations sake I’m doing it for taking hiking.
I have heard that dehydrating then vacuum sealing and freezing will get you over a year with it still being good. I have not tried this due to my wife being around we don’t get through a month of having jerky in our household.
I assume you are cooking the burger before dehydrating? I did some last year. After cooking I put it in the blender for a minute to break it down super small. Then I dehydrated and froze in a ziplock freezer bag. I expect it will be fine for this fall’s backpacking meals.
I’m definitely not an expert but that process worked for last years meals.