The simple explanation is it will not know. At midnight February 28th, the date will click over to show 29 just as it will do in March.
On months where the number of days is less than 31, you will have to manually forward the watch either by advancing the hours or by using the quick-set feature of the movement.
Don't worry, this is the same on the genuine models as well.
For homework, research annual and perpetual movements.