Firstly, in most cases your ECU is then locked to the device which was used to lock the ECU. The consequence is that in future only that device can be used to access the ECU calibrations leaving you dependent on both the device and its supplier for the remainder of the cars life.
This also means that no other tuning can be done by other tuners using their tools, and your Renault Dealer can no longer update your ECU anymore. The end result is you will need to purchase a new ECU, which by the way will no longer have a tune on it.
Please contact us for details on how we can help you get a custom local tune for your RS.