Did you store the battery charged during those 8 months? Storing lipos charged will cause them to die, the oxygen inside the cell pouches comes as a byproduct of the lithium plating itself to the anode, usually this happens from overdischarging, running them down too far at high amp draw, and storing them fully charged. The pack could be a year old before you got it too, which will exacerbate these problems once you start using it and if you store it fully charged.
If the motor cuts out likely the LVC is set to hard cutoff, this is good if you are comfortable with it happening, it tells you the pack is low, best thing is to cut throttle, bring the model round and land immediately. I set my ESC's to the highest cutoff setting, 3.2 or 3.3v usually, and hard cut, this way the modern batteries are more protected. Most modern lipo cells will maintain voltage until around 90% discharge, this of course means if your LVC is set too low the cell will be completely drained before hitting LVC, this kills packs very quickly.
Best to fly to a timer, if you got 4 mins set it to 3.5 mins and use it, otherwise you will be replacing batteries more often than you would like!
