You are possibly using a license key and control number for which QlikTech has set an expiration date (temporary license) that has passed. Can you check the validity of your license?
Was it a demo license? When you buy QlikView Server, usually the same license key and control number are upgraded. But that may not be true in your case.
All license has you maintenance date in it. If you don't renew you contact you are not allowed to install any new produce or updates after that date. This would look like this PRODUCTLEVEL;10;;2013-09-01
Also you can have a TimeLimit license and it will not work after the time has expired, and that setting would look like TIMELIMIT;VALUE;;2015-01-31
So, check you LEF and see which one has gotten you. If you want to send me the license key in a private email, I will check it for you