i have my garage at home, but the sticker gets stolen at work. and it’s a busy road where i park 
it usually get stolen from 9-5pm
That’s downright weird. Are there any surveillance cameras on the lot where you work?
This is starting to sound like a case of someone who is irritated with you for some reason and is just trying to cause you a perpetual headache, along with emptying your wallet.
Tape razor blades to the back of the plate, with the sharp edges protruding out slightly.
I would think the great idea of slicing it into small pieces would foil the person trying to steal the sticker to use as their own. Every one I have ever seen is a metallic like label that tears easily to make them hard to steal. Over time they get brittle and are very hard to remove in one piece. I’d think you could skip the sealing layer on top, once stuck to a clean subsurface, they don’t come off unless taken off on purpose.
If you sliced it into small pieces and then applied it to the plate, who would sit there and try to take every last bit off to steal it versus just moving on to the next car? Answer: someone who is doing it as retaliation or to cause you, specifically, some grief.
I second parking near some camera surveillance or get one yourself and record the culprit. I’d bet you recognize the face…
They’re doing that here in MN too, and we don’t even have much of a sticker theft problem because our stickers are so tamper resistant that they shred themselves half the time when you’re trying to put them on legitimately.
Mike, the OP wrote, “…I also bought a transparent license plate cover (a hard one) to protect the plate and the sticker…”
You don’t have to be from California to read. 
It would probably be illegal to do it at night since it wouldn’t be illuminated, but during the day, as long as it is visible, you should be fine.
The cops might not go looking for it, but if you report it stolen, and the criminals happen to get pulled over for something else, they will be able to charge them with this crime.
You might be surprised. Those who steal registration stickers might be dumb enough to drive around with a broken tail light or something.
Now, GA prints the plate number on the sticker…
Florida is doing the same thing, and I have never had a sticker stolen.
The reason it is easier to steal the stickers these days is because of products like one called “undo.” It allows you to remove anything with an adhesive back, and it preserves the stickiness. If you discover an error on an envelope after you apply the stamp, you can use this stuff to remove the stamp and it will still stick to another envelope when you are done. It’s also great for removing bumper stickers and inspection stickers.
You CAN put the plate inside the rear window.
Get a license frame with a lamp on it and run a couple small wires from your park lamp circuit up through a little hole you drill.
This will remain legal at night and is something my repo guys do because they have wheel lift mechanisms in place of the rear bumpers. They are certified by the NMDOT as legal inside the rear windows of these trucks.
Make a copy of your tag, put the copy on your plate, so when it’s gone, put another copy there. If you get a citation, go to court “not guilty” and take your receipts for prior tag replacement and current tag.
Just read st. louis had 1500 stickers stolen last year. It makes me wonder if anyone there even checks the stickers if pulled over.
Forget the retail plate covers. Go to place that sells plexi glass and get 1/4 inch thick or thicker piece cut to the size of your plate and they’ll drill the holes for you. Use tamper resistant screws requiring a special bit. or if you’re cheap. torx screws are not easily recognizable and cheap. Then take some two part epoxy and cover the indents. Unless they have a drill bit sharpened in reverse and the drill… that plate ain’t going anywhere fast.
as long as the plate cover is clear it will pass all state laws. Some states are saying put the sticker in the middle of the plate and providing the little frame, too. lol now they just steal the whole plate
Too pricy? A lot cheaper than moving or new tags.
actually i wanted to do that, but DMV warned me that it is illegal
Go to place that sells plexi glass and get 1/4 inch thick or thicker piece cut to the size of your plate and they’ll drill the holes for you. Use tamper resistant screws requiring a special bit.
Wow, that’s some great advice. Where have I seen it before?
pepito9123, after thinking about your situation, I don’t think anyone is stealing your registration stickers to use them. Otherwise, they wouldn’t have stolen the one you cut into pieces after you mounted it. I think someone at your job is deliberately messing with you, and he or she is simply throwing them away. He or she might have one or more accomplice helping keep watch on you so he or she knows it is safe to go out there with a razor blade and remove the sticker.
Spend some time thinking about who at work would do this. Does anyone have a grudge against you? Are there any pranksters at work? What about the kind of jerk who simply likes to wreak havoc? Have you stiffed a waiter at one of the nearby restaurants?
If you are good at reading people, and you can tell when someone is lying, try questioning people at work to see what you can find out.
So is stealing your tag sticker, but I think MG McAnick is right. Someone must be after you. Put the plate in the rear window, and see if they are willing to break in. You do have an alarm, right?
Fit
If they are just numbers, have them painted on and keep the real ones in the glove box.
Clean the tag and dust them for fingerprints if the numbers are scratched up.I agree that someone is doing this for some weird reason.
I would take a day off, park my car at work, jump into a co-workers car and wait with a camcorder.
In keeping with shadowfax’s advice of a camera, on EBay and places like that you can find these cheap Chinese both on-dash cams, and these little keychain and pen cams, that are under $100 (and I think I’ve seen a few as low as $30-40). They record to an SD card. Otherwise, I like the plexiglass suggestion.
What?
Exactly
The OP should ask co-workers if they have ever had their registration stickers stolen while at work. If–as I suspect–none of them has had a similar occurrence, then it is obvious that the OP is being targeted by someone who is seeking revenge.
Perhaps the only solution is to place the license plate inside the car where it can be seen though the rear window.