Most likely people reselling MSDN licenses (I think it's now called Visual Studio subscriptions). These are licenses meant for testing only (though entirely val

Most likely people reselling MSDN licenses (I think it's now called Visual Studio subscriptions). These are licenses meant for testing only (though entirely valid). Pretty sure you are not authorised to sell them and certainly not to use them in production. People either buy a VS subscription then resell the licenses piecemeal (costs about $1000, and you get 10 license keys for each product, so probably profitable), or they got a subscription from their day job and sell the licenses.