According to the international standard, the person performing live working should be instructed periodically and in a sufficient scope.
This means, that you’ll need to take this course on a regular basis to guarantee maintenance of your skills. You must always be able to perform live working without the risk of an accident.
It is up to the individual to define, how often it is necessary to repeat the instruction regarding live working – but in case of an accident due to lack of instruction, the company will be held responsible.