The warranty is 200cycles or the Time factor depending on location.... which ever comes first.
6 months is USA ... EU has 1 year and in some cases can extend to 2 years in fact.
But as to actual life of the packs .... The next part of my post is the information given to me by DJI themselves when I questioned them repeatedly for a definitive answer - as usual they tried avoiding the question like the plague !!
Their answer was finally (and not only from one DJI source)
Old FW actually limited the use of the packs to 200 cycles. Once the 'smart board' registered ZERO (that's 200 cycles completed) the board would shut off. (I know how to cheat the board and reset - but that's not the issue).
Later FW - they decided to let the packs continue, so 200 cycles does not automatically shut a pack down. But they would never answer what happens then - do I get a warning ...
One factor I have noted since that exchange with them - the cycle count on the packs does not agree with the number of charges made. The cycled count is actually LESS. Which indicates it does not just blindly add 1 when you charge ... that it may add a partial increment depending on the amount of charge needed.
LiPo's today even including HV format - should give you at least 500 cycles when well treated - even more in fact. It remains to be seen what the DJI do ...
If I was buying second hand ... I would want to plug in and see the cycle count and cell values.
Nigel