How do I import Final Express HD projects into Final Cut Pro 10.1?

I bought a new computer and had the migration assistant (Mac) transfer all of my programs to the new computer. I have FC Pro X installed in the new computer. The old one was sold. I have a lot of projects saved in FC Express hd, but am unable to open the program without a serial number, which I've lost. Is there a way I open them in 10.1. or a way to get hold of my serial number?

Thanks