If you have correct ECM keys, the channels will open. The purpose of having the autoroll function is to automatically update the ECM keys in SoftCam.Key file (if/when they change). It is basically automation of the process of adding new ECM keys. If you don't have EMM key/s, but have correct ECM keys you just add in SoftCam.Key, they will work to open channel.
ECM key is required to open the channel.
EMM key is required to update the ECM key automatically, if/when they change.