kindly guide me how to treat lipo battery when not in use for 3-6 months, just keep it uncharged or charged it once in 15 days or 1 month

kp

Store at ~3.85v per cell. (About 50% charge)
You can check after say 2 months, but my experience is that it will hold this voltage without needing periodic charging, and will not puff up either.

Charge or discharge your battery to ~3.8v as it is termed as storage charge and at this voltage the battery discharge/year is very less.
I have put my battery at this voltage since 4 months and it is at aame voltage.
Yes it is better if you check the battery periodically like once for couple of months.