The TKey is a small computer in a USB-C device form factor, that can run small applications which are loaded onto it. The purpose of TKey is to be a secure environment for applications that provide a security function. Some examples of such security functions are:

• Time-based one-time password (TOTP)
• Signing oracles
• Secure random numbers
• Encryption

There is no way of storing a device application (or any other data) on the TKey. A device app has to be loaded onto the TKey every time you plug it in.