Can i do Lot-Cost Adjustment after transfer to GL

Hi,

In Process Manufacturing Lot Costing Method, as it doesn't consider the period, if I run accounting in final mode and transferred the transactions to GL for that period, is it possible to change the cost of the lot in next period. How it will affect the transactions which are already posted to GL.

e.g.  I purchased Lot A for the raw material in month of Jan  for $ 10 per kg. Using this Iot, I  produced product Lot having Lot Cost $ 7 per kg. I have finally closed the period and transferred the transactions to GL. Feb, if cost of Lot A changes to $12 per kg then what will happen to the transactions in Jan for purchase and opm batches as those are already transferred to GL. If those will not get affected then what cost of raw material lot will be considered in Feb is it $ 10 or $