First of all they say practice makes a man perfect so therefore if you continue practicing, it will stick in your long term memory. Again, try forming MNEMONICS, with these 80 prepositions just for you to remember them always. MNEMONICS, are ways of remembering things in an easiest, fastest and quickest way: just by taking the first letter of each word and piecing them together to form a sentence, statement or a song. An example is this: My Very Eyes May Just See Under Nine Planets, and they are; Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. That is it, Stay blessed.
Practice, practice, practice. I had to learn them in 7th grade and I still remember them all. Alphabetically is easiest, that way you are much less likely to forget one. (And our list was 100 of the more than 150 possible words)