You now have the ability to set an “expiration date” for specific user access to files in Google Drive, Docs, Sheets, and Slides.
For instance, you only need to give someone access to your Google Doc for three months. So you share the document with that person and set access to expire in three months. If that person attempts to open the document after the expiration date has passed, they’ll be denied access.
NOTE: You’ll only be able to set expiration dates for users with comment or view access; you will not be able to set expiration dates for file owners or users with edit access.
This functionality, coupled with the Information Rights Management (IRM) features, should significantly increase the security of Google files.