So i got these as well my wife's number plate was found on the floor in front of her car after it looks like some one knock it off (blue marks on plate)
these arrived in plastic bag on opening you have a set of number plate sticky pads. so i got to getting these in place first off removing old ones was painful a little scrubbing and the old stuff was gone. now i have learned a trick over the years to help these stick stronger and that is to warm up with hair dryer not heat gun as plate will melt. once heated up i place on the plate evenly i continue to heat up and then removing the red backing (which was a pain) but finally done i stuck to the car, holding in place for a few mins the plate stuck well.
its now been on the car 24 hrs and its since been raining and the plate is still attached very happy