Wait, are you saying that the key you bought from Mridul does not work? And they won't replace it? Why am I not surprised...
These are keys from MSDN account from Microsoft offical website and they are safe and work for lifetime
Every user get one key if they want to buy, so there is no risk for closure.
I have till now not yet got a single problem in selling keys.
Thank you
Selling keys from an MSDN subscription is not allowed. Keys will expire as soon as the subscription ends.
http://answers.microsoft.com/en-us/windows/forum/windows_7-windows_install/selling-product-key-from-msdntechnet-and-or/cf40c328-67ce-49b6-bbb6-c28cda92c06e
So I change my stance from "the keys are most likely not legit" to "the keys are conclusively not legit".
There ya go. I said it.
PS. http://www.microsoft.com/piracy/reporting -> report yourself here if you want. Or wait for someone else to do it.