The trial version has the same fucntionality as that of the full version. All functions can be used exactly the same. You do not need a product key to use the trial version.
After the trial period has expired, only TuneUp Rescue Center and TuneUp Update Wizard are fully functional – the other components of TuneUp Utilities can no longer be started.
After obtaining a license, you will receive a product key to activate the trial version allowing full use with no fixed time period.