Per the FAQ's, yes but you wont be able to store anything new or any changes you want to make.
Can I access my data offline?
Yes. You can access your True Key app when you are offline, but you won't be able to save any changes or add new logins until you are reconnected to the Internet.
True Key will trigger offline mode on Windows when you login to True Key when there is no active internet connection. To check the functionality, you can disconnect your wifi or LAN connection and then try logging in.
Note: You should be on a Trusted device for offline mode to work on Windows. You will only be able to access the launchpad. Safe notes and wallets will be unavailable. Also you will not be able to add new credentials or make any changes to existing credentials on True Key.