I created an AMCAS account 4 years before I applied for this exact purpose. If you create an account you are in no way obligated to finalize or submit the application. As the application cycle period comes to a close you will lose the ability to access the application for the previous cycle and in its place will be the current cycle's application. There is a period over which you will be able to log into both. I think the only things that were retained were my contact information. Everything else had to be reentered (including grades). I haven't checked but I don't think I can log into the 2010-2011 application anymore. Well maybe I can but by the end of 2012 I probably won't be able to.