If some sort of "activation" method is needed, why not an option for either software activation or a dongle? I don't like dongles, but I dislike them a lot less than the software activation business.
At least with a dongle I can have two laptops. One in the office and to use in "safe" areas, one for use in the field and that I can afford to drop, have fried by stray nasties in a substation environment, etc but only one licence for Mathcad.
Bung
Life is non-linear...