network variabke throw exception

[johnnode7776]

Hello.

I have inherited a visual studio project that uses NationalInstrument.NetworkVriable assembly as following to read some variables. I can compile and I was able to read/query variables but after a few days: I am getting the following exception :   

which is basically telling me evaluation period has expired. My question is that do I need a measurement studio or any other license to read network variables or this is some project setting issue that is causing that ? 

Thanks for your help