yeah u need the handet if its the lil wrench symbol on a curtis meter (combined instrument)
u can reset the intervals to never come on or to come on in intervals of 250 hours up to 1000 hours
the handset dealer cost is about 400 US dollars and some dealers wont sell them
get ur local service guy out to shut it off and tell them to come with the handset although u should have the machine pm'd anyway

Hello Oliveira, as i, you are Portuguese and it is a pleasure for me help "my people".
About your question, in fact to turn off the service light of any Linde you must have a Linde specific hardware to do that. This is the correct way to do that, otherwise you can always take off the lamp, since that you respect the hours of preventive manutention, normally of 500 in 500 hours.