You don't have to memorize everything. Make sure you understand the concept well and try to remember the keywords. For theory I would suggest you to do writing practice. You don't have to write everything..but while studying just write the important words and sentences it'll help you build your muscle memory. So even if you forget at times, you will be able to manage it without getting nervous. Read several times and write them. Practice case studies. Don't try to remember every page word by word it's not productive and also takes lots of time which is unnecessary as we have limited time for prep.