With Holosun technology including power management functions such as automatic power off, it is expected that the battery will last 50,000 hours of active use.  You should rarely need to replace the battery.  In fact it should last about as long as its shelf life.  If you do need to replace it, use a high quality lithium cell like that which was supplied.  You may need to re-zero after remounting your optic, but it should be very close.