From their FAQ:

"14) Do we have to stay in Pittsburgh after the program ends?

Companies are expected to remain in Pittsburgh after the end of the AlphaLab program. Our goal is to help you build a successful technology company and to add to the critical mass of flourishing tech companies in the Pittsburgh region. We believe that Pittsburgh is a great place to build a company and after your experience at AlphaLab we are confident that you will agree."

Is this a legal agreement? It is still a bit surprising to me that you are still "expected" to tie down your company to a specific location. Maybe some ex-AlphaLab-er can shine in some light here.