WHAT IF I LOSE MY U2F KEY? Configurable and selectable fallback features include: SMS, Email or push notifications that will allow you to access your machine data in case of a lost key. A new key can then be enrolled to replace the lost key.
WILL THE OLD KEY STILL WORK TO ACCESS MY COMPUTER? No, only a single key can be active at any given time, so the old replaced key will no longer be able to access your machine. This ensures that stolen or missing keys can be deactivated easily.
CAN I USE MY KEY TO LOCK MULTIPLE WINDOWS MACHINES? Absolutely. As part of the U2F standard, as single key can be used for numerous applications, including iDKI, with no loss of security between applications. It is recommended though that each person has his/her own U2F key to ensure security to personal data.
WHERE ELSE CAN I USE MY U2F KEY? The U2F key for your iDKI can also be used to enable strong authentication on your Gmail, Dropbox, and Github account, as well as various enterprise applications. A single key can therefore be used to protect your personal as well as corporate data.

For a more comprehensive list of FAQ, download the full document here: U2F FAQ