anyone know how it works , i know you pay for the plate you choose but do you then pay a yearly subscription to keep it or is it just the one off payment
As long as the number is actually assigned to a vehicle you only pay once. However if you don't assign the number, but wish to retain the right to do so, you have to pay £25 per year to hold onto that right:
https://www.gov.uk/personalised-vehicle-registration-numbers/overview