When I order software online, I'm always surprised to see my confirmation email and my registration code come without an invoice.

Invoices are generally useless for individuals, but they are a necessity for companies.

They are required because your local doom kommando fiscal administration will ask for them as a proof you did indeed spend the money. And before they ask for them, your accountant will because if you want him to put his John Hancock on your anual report, you better make sure it's pretty clean of vague, non-business releated entries such as "DB9 leasing" and "Casino losses".

The invoice must have the name of the company, its registration number, an address (including the country), the name of the customer, the name of the customer's company (if any), the items list with a clear and consise description for each - don't scratch your head as long as the word "software" is in the description, the accountant will understand what it's all about - a price and finally the taxes and a grand total. Export that in a printable format (PDF is a de facto standard) and attach it to all your confirmation emails.

What I just said might sound extremely silly, but for ten software licenses I bought I received a valid invoice only three times. Generally speaking I'm more inclined to do business with companies that make my life easier.

Make sure you have all the details of your business process straight.

By the way, Hi! How are you doing? Long time no see! Here, we're going great and are working very hard on our first product!