Why is it that for my 48 hour demo it says I have less than an hour to play it?

I downloaded the sims 4 demo a while back waiting for a time where when I was not at work to play it for the 2 days that I am given, I go to download it so I can play in the car on my trip and it says that I have less than an hour once I open the game. How can I get my full trial back? It takes a long time for the Sims 3 to load on my laptop so I figure it will take most of my time up of my "less than an hour"