He raises a fairly good point about how in the commercial software world, we depend on serial keys amongst others. Ubuntu is way less dramatic as it is free-as-in beer: there are literally no costs or efforts involved when for example setting up a new machine or recovering an old one.
Software corporations such as Microsoft require you to use a license key or serial number, every time you do a fresh install of their products.
In fact, serial numbers and license keys are a way for Microsoft et al to lock their clients in. Of course you can buy their products in any electronics shop, but when you are a developer you just buy a license through MSDN, Microsoft’s developer service portal. On MSDN you can procure different types of subscription levels. Say you want to download SharePoint Server: how will you figure out which subscription level you need? Well, there’s one way: the subscription chart that compares the different subscription levels. Based on that information, you would go for Visual Studio Premium with MSDN. An easy job, isn’t it?
However, when you actually purchase the subscription you will be presented with many more options, such as software assurance, languages, number of users and edition (Ultimate, Enterprise, Empower, Retail, Volume Licensing). So cunningly, product availability does not depend on the subscription level alone. And there is no easy way for you to check if that particular software is available through a certain subscription level. There is a way though, and that is by browsing to the Subscriber Downloads section and then searching your product. In the details, you will find out if your level qualifies. Don’t be surprised yours doesn’t. Yes indeed, subscription levels require an in-depth investigation.
As a matter of fact, in large institutionalized companies, licenses are usually purchased through a preferred vendor. You have to work and deal with them. Well, you better be specific enough. Give them the right instructions, as it’s much more complicated then it looks like if you need to acquire a particular commercial software through a license. Forewarned is forearmed.