GST Registration for Rice Mill

My client is running rice mill and is receiving PADDY from customer and is processed to rice and gives it back to customers.

He gets commission for the process from customers. He also some time forward to other Modern rice mils for the same process in case if can not do from his rice mill.

In this case, is he mandatory to take GST registration as his counterpart rice mill ask for GST No.

Pls resolve this query. Thanks in advance