Do I need numbers or stickers on my keys?
It is not necessary to use numbers or colours stickers on your keyboard, as DecPlay teaches you how to identify the note numbers by reference to the patterns of black keys.
Labelling the keys is optional, but is highly recommended as it will speed up your initial progress.
Ideally use stickers, but non-permanent markers (eg dry wipe / whiteboard marker) can be used instead, if they can be removed without leaving a mark, after a few weeks or months
Once you are familiar with the keyboard, you can remove the labels and identify the keys just by looking at them, which will enable you to play on any keyboard or piano, not just your own.