Last weekend I had a brilliant cooking idea – to treat my family with a delicious Japanese curry. During my shopping tour around Waitrose, I dropped a couple of curry boxes in my basket alongside the other essentials on the grocery list, then sailed through the self-checkout and went home humming a happy song. Or was it a sad song?

I don't really remember that detail for I was thinking about the security configuration of my web servers at the same time. Typically for a male creature, I am not so good at multitasking. Especially at clear thinking about a number of important topics simultaneously. One of them being that curry for the family supper.

On arrival, I realised that the curry packs I picked up were just a sauce concentrate. And I was still missing all the other ingredients. Unfortunately, all the stores in our midsts close at 4PM on Sunday. You could have guessed, that definitely didn't go well.

And that reminded me of an article I wrote ten years ago about corporate licences for Microsoft Windows. And you know what I realised? Not much has changed since 2009.

See, corporate, or "volume", Windows 10 licences are much like that curry sauce. They alone don't grant you rights to deploy Windows 10 Enterprise. All you can buy through an Enterprise or MPSA Agreement is Windows 10 Upgrade. And there's alway a risk that the other ingredients for the perfect family supper are not in your cupboard, and you have to go back to the store.

To be eligible for Windows 10 Enterprise Upgrade, your computers must already be licensed with a "Qualified Operating System", which you are normally expected to acquire pre-installed with desktops and laptops. See, that "normally expected" part isn't really a common knowledge. And to make things just a little more complicated, it cannot be just any operating system, even if it is from Microsoft.

For the majority of us, our computers must come with Windows Professional pre-installed by the manufacturer to qualify for an upgrade to Windows Enterprise.

If you have done this mistake in the past, or if you work in SAM or licensing, or even if you are just that lucky person that always learns from other people's mistakes, you may be thinking at this point: "C'mon, everyone knows that!". Well, apparently, not everyone. Not according to what I witness quite regularly. Just a couple of hours ago I was looking a purchase order, in which half of the desktops were specced "naked" – without an operating system. And that document was produced by respectable IT procurement people working for a respectable organisation. Luckily this time, we managed to stop the PO in its tracks.

But what would have happened if they bought those "naked" PCs? If we go back to my curry analogy, it would be like buying an empty saucer pan. You have your shiny pan, you have your curry concentrate but you still cannot make a curry. Literally, you don't have rights to deploy Windows 10 Enterprise Upgrade because there's nothing to upgrade from. So you go back to the store. Depending on the availability in your geographic location, you options may vary. You may opt for a full Windows Professional licence for each computer; and to do so you would have to go to a retail facility because they are not available through the corporate channel. You may otherwise decide to sign a GGWA ("Get Genuine Windows Advantage") Agreement.

The same condition applies to computers acquired with Linux. Mac OS X may qualify in some cases but please always check the latest Product Terms.

In my experience, the most devastating moral effect of this revelation has always been on the customers who purchased laptops with Windows Home edition. On those who have bought their hardware with Microsoft Windows pre-installed, just not the right flavour of it. Sorry, but you cannot make a chicken curry with just cauliflower and potatoes. Back to the store then. Again, depending on your geographic location and eligibility, you may be able to purchase a Windows Home-to-Professional "edition transition" key. And if there is no such option for you where you live, you are back to the "naked computers" scenario.

I must add a note here that some categories of customers may be allowed to upgrade from Windows Home depending, for example, if they qualify for Academic licensing. Doubts? Always check Product Terms.

It is one of those mistakes that you, personally, will never repeat again. Unfortunately, it does not always apply to organisations. If there is no process in place, if procurement of hardware and software is not under the centralised ITAM department's supervision, someone may eventually purchase "naked" computers again. I see this happening all the time, and we are in 2019.

Let's be honest, the whole Windows licensing policy is counter-intuitive. Why, oh why, dear Microsoft, don't you offer full operating system licences in the volume channel? But while there is a good chance that it may never change, we can still learn from other people's mistakes and be prepared.

Always read the label. I didn't, hence we had to resort to an apple crumble thanks to the basket our lovely neighbours had put outside of their doorstep with the fruits from their garden. Not that I complain. The crumble was marvellous. And what's not to love about apples? But to finish my curry quest I still have to go back to the store for the other ingredients. If it says "Windows Upgrade" on the tin, it is probably not a full product.

Have a shopping list and develop good purchasing habits. Have a robust process in place, and have all your software and hardware acquisitions centrally approved. Please, don't be mislead by the name of "Software Asset Management". A successful SAM programme should always be looking after hardware assets as well, at least from the compliance and licensing costs perspective.

Happy cooking.