The OpenCrypt shopping cart/basket system enables us to integrate shopping cart buttons anywhere within our web site content. These can be used to sell any product with a fixed fee and can be customised to work in numerous different ways, when selected the item is added to the shopping cart and the button can change.
We can also setup custom responses to shopping cart purchases, for example adding records to your software licensing database automatically or sending files via email after purchase. Add to cart buttons can have customisable quantity inputs and products can also be assigned weights so shipping costs can be calculated based on the products purchased. You can also detect if a user has purchased a particular product and display different content as you require.