Breast milk is very complex in composition. It can change during one breastfeeding and it will change as the baby grows. However, the stores sell the same formula as for the first month, which is for the sixth.
My concept of the formula takes into account the fact that the formula has to be more adapted to the child's height and will change its composition every month.
There's a spoon in the box for every month. This has simplified the feeding scheme.