Historical purchases are different from purchasing history entries!

If you completed the procedure To add a vendor card, you entered monthly purchases totals for your vendors for the months before you began using Plus. That information is useful for reporting purposes, but is optional.

The historical purchases you enter are different -- they're purchases that you made before you began using Plus but haven't fully paid off yet. Because you still owe money to vendors for these purchases, it's important that you record them in Plus. This step isn't optional!