Techsmith had a limited time offer for free licenses for old versions of SnagIt and Camtasia. The offer has expired - so you are too late. Sorry - next time.
Even if you want the current versions it paid to download and install the old version because you could then upgrade at 1/2 the price of a new license. Techsmith's hidden page for downloading old versions is http://www.techsmith.com/download/oldversions.asp .
You were also able to register for a free license key for SnagIt 7.2.5 (the current version is 8.2.3) at http://www.techsmith.com/snagit/ukdn.asp and for Camtasia 3.1.2 (current version is 5.0) at http://www.techsmith.com/camtasia/pcpls.asp . These are full licenses, not 30 day trial versions.