Uninstall the program and reinstall it. This is basic method used to keep a program running after its trial period has expired, but it will not work will all software. Many software engineers program trial software to expire at the end of a given time and reinstalling the software will not restart the clock.
Adjust the date in the date/time settings on your computer to a date previous to that of the installation date of the software
Install application-monitoring software that keeps track of system changes that occur during software installation. Use the monitoring software to delete the data related to the expiration of the trial software.
Back up your computer's registry before you install the trial software. Once the software's trial period expires, restore your computer's registry. This method should only be used if you are experienced with computers and with making changes to the registry. If you do not know how to edit or manage the registry, do not use this method.