To extend your trial, you will need a trial extension key. You can go to this link for a trial extension.
NOTE: If the your trial extension key does not work, it is because you've already extended your trial beyond the allotted usage/time. You can request a further extension at: Sales@SoftInterface.COM. Response is usually immediate.
Once you have your trial extension key run the software program (e.g. 'Convert Doc', 'Diff Doc' etc.). Do this by clicking on one of the desktop shortcuts or going to the Start\All Programs menu within your operating system as shown below:
Then, from the program you just ran select the HELP menu item, select the ABOUT menu item as shown below.
There you will see a place to enter the trial extension key below: