How long will the ear tag last?

Your ear tag is designed to operate for 3 years.  Because the ear tag is so small, the internal battery will become weak and no longer store energy after 3 years.  This is very similar to your cell phone...  As your cell phone ages, you will notice that the battery will not stay charged as long as it once did.  This is the same concept for the ear tags.  

At the end of the 3 years you can simply cut the tag off the animal and replace it.