Vehicle registration
A vehicle must be registered before it is used, and registration is what the bluebook records.
A temporary registration certificate is issued while the permanent one is prepared, and it remains valid for a maximum of one year.
If a registration lapses, the vehicle can be re-registered within five years of expiry. After that the registration is gone rather than dormant.
A foreign vehicle entering Nepal on a temporary basis may be permitted for up to six months in total, whether taken at once or cumulatively.
The number plate is part of registration. Driving without one is an offence the traffic police can act on immediately, and the letters on a plate identify what kind of vehicle it is.