Calculate max quantity bought if range of dates<days determined by another cell.

In column A the codes of products are given. B is the number of days by which if the date range is < this number, the quantities should be added. Max quantity is the sum of such quantities, given date A2-A1<B2.
However, this only calculates the max quantity for 2 consecutive dates. I need a formula for a varying date range, within each different code.
The attached file makes it easier to understand.
Please help!!

Hi,

You need to explain in detail the logic behind 'Quantity' & 'Max Quantity'.

Also,

B is the number of days by which if the date range is < this number

, what you mean by this?

'Quantity' = number of items bought for each date given in Column C.
Codes represent different items. ie; 1001=apples, 1002=bananas...
Max Quantity = sum of quantities for a certain item, if the range of dates the item was bought in is less than 61days.
However, the formula I have used, doesn't allow for a range, just 2 consecutive date differences.

Other forumlas I've used in other parts of the spreadsheet are:
=IF(A2<>"";MAX(OFFSET(L2:M2;0;0;IFERROR(MATCH("*";OFFSET(A3;0;0;COUNTA(L:L)-ROW()+1);0);COUNTA(L:L)-ROW()+1)));"")

=IF(AND(MAX(OFFSET(L2:M2;0;0;IFERROR(MATCH("*";OFFSET(A3;0;0;COUNTA(L:L)-ROW()+1);0);COUNTA(L:L)-ROW()+1)))>1;A2<>"");ROUND(MAX(OFFSET(L2:M2;0;0;IFERROR(MATCH("*";OFFSET(A3;0;0;COUNTA(L:L)-ROW()+1);0);COUNTA(L:L)-ROW()+1)))/2;0);H2)


Just in case they serve as any help.