The 100 user upgrade is applied to the system for which it was purchased and cannot be transferred to another NV7100. However, If you thought that you had purchased a 100 user NV7100 but instead received a 30 user system, I would contact your reseller to make sure they shipped you the correct device. Once you have a 100 user system you can load your backup configuration again to restore those extensions that have been erased.
Having only ever worked with a 100 user system, I was under the impression that there were no other configurations. Thanks for the info Charles!