You can retain any number under your name by registering it called "MUMAYYAZ"
The charges include around QAR 500 for Mumayyaz + QAR 300 for a new Number Plate (Randomly selected by the Computer) for the vehicle whose number plate has been made Mumayyaz.

The Mumayyaz number plate can be fit to any vehicle whenever you wish abd the existing number plate shall be seized by Muroor (Traffic department).

Hope this answer your query