Discussion Board for collaboration related to QlikView Deployment.
Could you please expand your question at bite more. Is this a user on a server or is this a local client? Expired, do you mean you are not paying maintenance anymore or was this a trial license?
As the License key is perpetual the server would work just as ASHFAQ answers. But the would loose the possibility to get support and future upgrades. My recommendation would be to get them back on support as quickly as possible.