Hmm, I do not remember exactly. But when I had a free e-learning voucher with an MSDN Account, I simply logged on to the e-learning site (it was the same life account, that also had the MSDN subscription) and when I "bought" the course, I directly
got it without the need to pay it.
But it is already some time ago, so I cannot remember all the details. (And I decided that these was nothing really usefull for me. So I never investigated that more in detail.)
With kind regards,
Konrad