Solution
There are two ways to successfully register or activate LabVIEW SignalExpress Limited Edition (LE):
SignalExpress License Dialog
On opening SignalExpress within the first 30 days of installation, you will see the following License Dialog Box:

1. Select
Register Limited Edition to register/activate SignalExpress LE.
2. Continue through the remaining pages with the default settings.
3. You should now have access to SignalExpress.
NI License Manager
1. Launch NI License Manager by selecting
Start»All Programs»National Instruments»NI License Manager.
2. Click the
Activate button in the toolbar after selecting SignalExpress Limited Edition in the product tree and complete the steps in the activation wizard.
3. Enter the appropriate serial number required to activate SignalExpress LE from the list below:
SignalExpress 2.0 - S12X86753
SignalExpress 2.5 - S13X86753
SignalExpress 3.0 - S14X86753
SignalExpress 2009 - S14X86754
SignalExpress 2010 - S14X86755
SignalExpress 2011 - S14X86756
SignalExpress 2012 - S14X86761
SignalExpress 2013 - S14X86764
SignalExpress 2014 - S14X86771
SignalExpress 2015 - S14X86772
Once activated, you will be able to use SignalExpress LE.