But why would someone pay for the software if the seller is not adding any value to to product?
A: the mistaken belief that the seller is adding value, even in the face of all evidence, which is caused by a capitalist tendency to believe that all prices are inherently just
B: disbelief in the idea of anything worthwhile being free, which is caused by the capitalist tendency to attack the free exchange of goods and services.
Oh, because if the month you chose has less than 31 days, it’ll assume the 31st of September is the 1st of October? That’s reasonable.