I'm afraid you don't really understand what you're writing about. Terms such as marginal cost and average cost are used only for goods, which are sold on a free

I'm afraid you don't really understand what you're writing about. Terms such as marginal cost and average cost are used only for goods, which are sold on a free market for a price. Your examples are services or freeware, you can't calculate marginal cost and average cost for a service or freeware.