Sometimes the applications require an online server to properly activate the application. If you don't have WiFi and it's urgent to use the software, simply attack a WiFi dongle and connect to the Internet. It's the fastest and most reliable way to connect to the Internet, plus it's very cheap. For example, a standard WiFi dongle will cost somewhere around 5$.
You are prompted to enter a serial number in Gel Quant Express because it can't reach the activation server.