What kind of students? School or university? Did you feel like you knew them or were they unrelated dream characters? Did they physically appear or did you only hear about them or have dream memories of them? Did they wear anything special maybe like uniforms or what made you recognize them as students?
Who made the promise: You or somebody else? To whom was the promise made? Was it a very serious promise or more or less for fun? Why did it have to be changed? Was it impossible to keep maybe?
Just some questions to get you thinking. You don’t have to post all the answers here, it’s for you.
If you cannot immediately write down your dream then try to solidify it in your memory after waking up. You can do that by going over the memory multiple times in your head and digging deeper into the memories and details of the dream as you do. Also I often think about what I will write down later in my DJ when I’m in such a kind of situation. Or think of a title for the dream already and memorize the title in particular.
If you really mean “search“ with your phase, as in spending a considerable amount of energy to obtain your DJ, then you should pay more due diligence to the advice of putting your DJ right next to your bed 