Close your internet conection (or block all temporaly with your firewall)
2) Go to this folder: "C:\ProgramData\TechSmith\Camtasia Studio 8\RegInfo.ini."
3) Edit 'RegInfo.ini' file and change all for this:
[RegistrationInfo]
RegisteredTo=Any Name
RegistrationKey=KC2AC-ADZAM-CSWAW-NF6XZ-N56F8
ValidationData1=
ValidationData2=1
ValidationData3=1