Step-by-step explanation:
The reason behind the dropping off of sales in the current month as compared to the sales of last month when they were at their highest, could be that the product has reached its maturity phase and now it is the decline phase for the product. In a product life cycle, there are different phases like Introduction, growth, maturity and then decline. In this scenario, the product might have achieved its maturity and now the market for this product has become saturated and there was no room remained for the sales, then the sales might drop off drastically.