Hello Julia & welcome!
To answer your question, no the trials do not expire after a set time frame, they just offer two weeks worth of curriculum.
Have you downloaded and read through the free e-books on the homepage yet? They are wonderful and will get you started on the right path. Dig around through the forums too, you will find lots of great information!
I wish I had known about prental learning before my babies were born. Here's an article on fetal hearing.
http://www.ehow.com/about_5312868_development-hearing-human-fetus.html One way to start early learning now is to read the same book and/or sing the same song to baby everyday between now and your due date. When baby is born, he/she will recognize the story or melody and find comfort in it.
You can also play "kick games" and teach the baby to kick where you press gently on your belly. And have the babies dad talk, sing, or read to baby too to allow them to get to know each other. My husband talked to our babies nearly every night even before we knew about early learning, just because he loved them so much and it was fun to see them respond with kicks and such.
Good luck and best wishes for an easy labor!