no your command is NOT to change it to DNA licensing, it is to activate the license that DNA can manage the device
this is traditional right-to-use licensing ,
-> YOU are responsible that you have the right to use (purchased) the license that you activated.
there is no technical limitation, no registration, no license file needed.
read this post
where the answer is given
Smart Licensing is supported from 16.9.X and later. If the appliances are running earlier firmware versions, Smart Licensing is not supported and no harm will happen without Smart Licensing.