Let's suppose that you have a licensed copy of an Windows Vista/7 but lately you have installed-activated/uninstalled it for several times. At some point the Microsoft Activation Server just get bored and says "OK, if you want me to activate your license then please pick up the phone and call me!".
What if you get bored (or you are just lazy) to call Microsoft and to justify yourself and to ask them "Please, can you activate the copy that I bought legally? Yes, I have an invoice, in fact I have 10 invoices because it happens that I bought more copies than I'm using right now. No, I'm not a software theft, I cross my heart and hope to die!"
Well, in that situation (let me make myself clear: when you both have the legal right to use that piece of software and you don't break the EULA) you could just try to exploit one of the Windows Vista/7 weaknesses. In fact you could try to exploit more than one, I'm sure they are. In plain English you bypass Windows Vista product activation
So you got a message like the one below (or similar):
I would recommend you to follow the steps already described...well, please give me at least a Like so that I can open this door for you
[!] WARNING [!]
I would not recommend to anyone to try this procedure to gain the access to use an unlicensed copy of Windows. In fact, when dealing with licensed software (like Windows), I would strongly recommend you to contact your software provider to ask it if you are allowed to do something like that or not. I wrote this article only for myself for research/educational purposes.
Now, if you think that this article was interesting don't forget to rate it. It shows me that you care and thus I will continue write about these things.