You have a reference computer named Computer1 that runs Windows 10. You plan to run sysprep.exe several times on Computer1. You need to prevent the Windows Product Activation clock from being reset…

Setting a dummy ProductKey value in Sysprep.inf does not affect the rearm process; it only substitutes a product key and does not prevent the activation clock from resetting.

Setting SkipRearm to 0 is the default value, meaning rearm will occur normally and the activation clock will be reset on every sysprep run.

Using an all-zeros ProductKey in Sysprep.inf addresses key substitution, not the activation clock, and does not prevent the rearm from occurring.

Windows allows a limited number of rearms (up to 3 by default) before activation is required. Each sysprep run normally triggers a rearm, decrementing that counter and resetting the activation grace period. Setting SkipRearm to 1 in the generalize pass of Unattend.xml tells sysprep to skip this rearm step, preserving the activation state across multiple sysprep runs. This is the Microsoft-supported method for repeated sysprep use on a reference computer.