Hi assuming you had a Valid license provided by cisco then you only need:
Acces IDM https:// your sensor IP address
Confiuration_>Licensing->Select the location to retrieve the license from ( in your case it should be from file )
Browse to the specified file and click on Update license. This is all you need
do a show version to make sure ..
If you are still having problems then I suggest you open a TAC case.
I hope ot helps ... please rate it if it does