I believe the TI marketing group has this right on.
To quote the web site "Get a copy of TI-Nspire Computer Software –
Teacher Edition and participate in an exciting new program called
Learn & Earn. The TI-Nspire Learn & Earn program will give you an
opportunity to own TI-Nspire or TI-Nspire CAS Computer Software –
Teacher Edition ($150 value) for free. Simply request a CD, take a
short online course to learn about TI-Nspire technology and complete a
brief quiz. When you are finished, TI will send you an activation code
to turn your trial software into a full, single-user license copy of
TI-Nspire Computer Software – Teacher Edition."
Here is the web link
http://education.ti.com/educationportal/sites/US/nonProductSingle/global_forms_nspire_trial_CD.html