Milk upgrade

Hi! Just wondering , how many of you mummies upgrade yr child's milk to stage 3 once they turn 1? Is it necessary to change? My son is 13 month's old and I'm still feeding him step 1 😅 he eats really well and besides his regular milk intake , i do introduce fresh milk , soya milk and juices. Is it okay if i just continue feeding him step 1 till it's time to wean him off milk? #1stimemom #pleasehelp #advicepls