The Trial lock marks the license as a trial, it's used to provide prospects an evaluation license. The Trial Lock doesn't set any time period upon which the trial expires, it merely identifies the license as trial and as such can be used to limit access to functionality or change the behavior of the application according to the business model applied.
You may use the Trial Lock together with Time Lock in order to set a time period for the trial, thus limiting the time a user can evaluate the protected software. You may also add a Feature Lock to limit access to functionality during the time of evaluation.
During license validation Agile.net will attempt to validate every other license on the machine that it can find before attempting to validate a trial license. Because of this, you can issue a registered license to the user and it will automatically take precedence over the trial.
You may inquire a license if it's trial by calling the AgileDotNetLicense.IsTrial property. This property may be used to limit access to functionality or include any trial limitation you'd like to impose for prospects using the evaluation license.