When your workbook is locked with Hardware Based Activation Code protection option, you can specify trial period for it by entered number of days to request Activation Code. But if you need more strict time limitation, for example you do not want your file to be used after a specific date, you can combine Hardware Based Activation Code protection with Trial Period protection.
Option Combine with trial period protection allows to specify Trial Period options.
These options are same as for usual Trial Period protection option.
When locked file is opened on customer's PC, LockXLS Runtime checks if Hardware Based Activation Code options allow to open it. And if file can be opened LockXLS Runtime checks Trial Period options. File is opened successfully only if both options allow it.