I have been using Mathcad ever since Mathcad 2.5 [circa 1988]. My most recent version was Prime 3.1 on my laptop, with the support package. About two weeks ago it crashed and I could not recover anything that was on that laptop. I purchased a Surface Pro 3 that is becoming a widely used engineering platform and asked support to assist in installing Prime 3.1 on my Surface. Support was not able to activate the license as Surface does not have a physical ethernet card. Surface does have Wi-Fi and it also has a USB port that can be connected via a wired ethernet adapter.
It is proposed to associate the Mathcad license with either of the above. I am personally familiar with a large number of engineers who use Surface in a variety of engineering applications.
Please see the discussion on the same subject in Mathcad community. Thanks.