Transit Permit Registration

Hi. My trip is from Los Angeles, CA -> Beijing -> Japan. My layover in Beijing will be for 14 hours, but I don't plan on checking into a hotel. In this case, after I arrive and obtain the transit permit at the airport - do I have to go to the police station to register myself personally?

Also, my return flight is 6 days later from Japan -> Beijing -> Los Angeles with a 5 hours layover in Beijing. Do I have to reapply? or can I reapply if I want to leave the airport?

Thank you!