why the softwares have the licsence

Of course it is necessary and important. License agreement is the software producer or manufacturer's security that the terms and conditions are met by the person using it. Hence, it is likewise one way to protect their product from being copied and reproduced by unauthorized company or individual. The license agreement is per se a contract and when you agree into it, you are bound to meet the contents thereof and may be sued for not abiding with the agreement.