The most common cause of an activated Surfer, Grapher, or Strater license disappearing from the License Administrator is a change in the locking code for the server computer. Our licenses are locked to the MAC Address, UUID, and CPU Info String. If any of these criteria change then the locking code for the server computer will change and previous activation will no longer be recognized as valid.
The licenses can be restored to the server by deactivating the previous activation through our My Account portal and then activating the license again in the License Administrator.
If the server change that caused the change in locking codes will occur routinely, please contact our support team to let us know what locking criteria will be changing. We can then create a custom license that will better accommodate your server setup.
If your licenses are no longer listed in the License Administrator, but you do not believe the locking code is the cause, please click the Create licensing support file link on the Settings page and send in the file for further investigation.
Updated November 13, 2019
See here for information about a concurrent-use license disappearing from the license server: Expired Trial message when single-user license disappeared from computer