If you haven't been doing so already, it's definitely a good idea to keep a log of all the things you learn in Muay Thai (just like in school).
Personally, I'll (try to) write exactly what the pads or drills were done each class, and sometimes I'll write down how I felt doing each set of pads/drills
This way, I'll always have a reference for techniques, as well as a way to keep track of what kind of things to work on if I'm training alone. It is also useful for keeping track of your progress (did my left kick feel better today than it did last week?).
The last thing I might write is any kind of comment or statement that an instructor makes that really stands out to me. This can be an analogy for a technique, or something motivational that relates to whatever I'm working on at the moment.