I just got a new car, and immediately thought up the mnemonic “peekaboo” for PKB.
My last car was HJZ - HoJoZebra.
In Texas we change license plates with the car - new (used) car, new license plate. I remember Ohio had a “keep your plate” law or somesuch - is that right?
We usually get vanity plates. 
We got standard plates from the dealer for our new little red putt-putt, and we were stuck with them until our vanity plates arrived. Until then, I remembered the plate this way:
[digit of the month I was born][digits of the year Mr. S graduated from high school][abbreviation of the month we met]
The van we just bought also came with standard plates, but I haven’t decided on a vanity plate for it yet. In the meantime, it’s [phone exchange of a city where we used to live], followed by some letters that I haven’t invented a mnemonic for yet.
Before we had vanity plates, though, I was pretty good at remembering random plates. I tend to see alphanumeric strings as “words,” and so I can easily picture and recall them. I know both Mr. S’s and my SSNs and driver’s license numbers (in WI they’re pretty long), and I still recall the plate numbers of some of my co-workers from 15 years ago, because I parked behind them so often.
Why do you need to remember your car’s license plate number?
Somehow that must be an incredibly stupid question.
In case it gets stolen, so you can report it to the police?
I thought of that, but I have all the tag reciepts in a certain place (titles too). The tag # is on the reciept.
Mine’s satanic so it’s easy to remember- all the numbers on the plate are 6s, plus two of the three letters are my old initials!
My vanity plate use to be my username.
I don’t. :o
I try to, by reading it to myself when I see it, but I can’t bring it to mind right now, so must not be working.
I write it down and keep it on me, in my wallet/purse.
Hell, the DMV has that info, should it ever be needed. I have a lot more useless trivia to fill my brain up with, thanks.
The letters are a brand of electronics then it’s a two digit number X, then another two digit number X+23.
“lipstick and cigarettes have 637 cancer causing chemicals” was my DoD decal.
I have only needed it when I check into a hotel, so I usually lean back and read it out of a window or a door, then write it down for them.
And if it gets stolen while you are on vacation hundreds of miles from the filing cabinet in which you filed them…
Vanity plates solve the problem quite handily. Although school security did wonder why I was advertising “foreign sex” on my plate.
I remember the original plate number of my first car (and the vanity plate that replaced it, of course), my first motorcycle (before the car), my second motorcycle, my dad’s identical motorcycle, my first Willys, the first Porsche, my fourth motorcycle’s California plate, my fifth motorcycle’s California plate, my Jeep’s California and Washington plates, the Prius’s plate, the MGB’s plate, the N-numbers of both of my dad’s airplanes, the N-number of the first plane I logged time in, three of the helicopters I’ve flown, and my California driver’s license number. Also all but the last four numbers of my first credit card.
I guess I have to call home. But, hey, we’ve got six cars with tags. I’m not sure I could remember them all, even if I wanted to.
Obviously, I’m not as smart as Johnny L.A. ! 
Smart? It’s probably just some form of horrible mental disorder.
I drive a silver 2006 Honda CR-V, and I live in Seattle. I memorized my license plate number so I could distinguish my car from all the other cars just like it in the parking lot.
Seriously. I’ve also pulled up to a traffic light to see one silver 2006 CR-V in front of me and another behind me.
To answer the OP…I remember the first three digits because they’re a common telephone exchange in my hometown, and the three letters because they sound like a phrase when you say them aloud.
I could never remember my license plate number. Ever. Which was a real pain in the ass when I would have to fill out parking forms (for school, for work, for my apt building) and of course the most important thing is the number. Then I got a black Honda Accord and it feels like there are about 10 million of them on the road. So when I moved to Utah, I got a vanity plate. Now I’ll never lose the Wilco-mobile…
It’s not a vanity plate, but I got lucky and my plate number is the same forwards as it is backwards. Easy-peasy.
I just… remember the license plate number? I don’t have a system or mnemonic. I’m just good at remembering short strings of numbers and letters.
Oh, and, yes, I recall that Ohio doesn’t require you to get new plates for new vehicles. You can just transfer the plate from an old vehicle to a new vehicle (provided that you document the transfer with the BMV). But, you can just get brand new plates, too.
In some places in the UK, if you park in a public parking lot, you have to punch your plate number into the machine that gives you your ticket.
This prevents you passing the ticket that still has time on it onto another person. Greedy bastards.
It took the police about 30 seconds to get the info for my pickup when it was illegally towed when I was out of state.