There are many ways to secure a door. We sell a lot of electronic door locks for residential applications. It's a lock where a code is entered and no key is needed. You can use multiple codes, one time use codes and on some models, codes that will leave the door unlocked for a period of time. It's great for homes with kids, homes that are rented out and offers the option of remote lock and unlock as well as code changes.
Just give us a call. We would be happy to discuss the options and install a system that will work for your specific needs.