I use the Mosby's pharmacy memory cards. I keep it in my purse and pull it out whenever I have a spare moment. I also make my own drug flash cards with drug class, action, therapeutic effect, side effects (both mild and serious), and any other pertinent info. For me memorization is repetition. Once I become familiar with a drug class, I start coming up with silly sayings that's probably doesn't sound much to others, but it helps me remember.
Buy a drug book and know the number for the hospital pharmacist by heart
As you practice as an RN you will become increasingly familiar with the meds you give on a daily basis. For the times when something odd comes up, for me it was often Parkinson's meds or the like, you can get your book out and review them quickly. You will be surprised how much you can quickly recall with just a brief review. This also allows you to see any changes to administration techniques or side effects. I used to buy my unit a new drug book every year, however you can also get apps for your phone, but we all know how others feel when we pull out our phones even for work related tasks.
You'll never learn all of them. There are thousands of medications and new ones are added daily. It's unsafe to try to memorize medications and apply that knowledge to practice. In real life nursing, you'll need to look up your medications before giving them in order to ensure you are doing so correctly.
For school, focus on classes of medications. They usually have similar endings and on NCLEX or tests you'll probably be able to figure out the class of the medication by the name and/or other details in the questions. Each class of medication (ie beta blockers, ace-inhibitors, penicillins, selective serotonin re-uptake inhibitors, etc.) works similarly and has similar side effects.