Brother google says it all: http://www.lot.com/es/en/carry-on-baggage

Having flown 300+ times on LOT I have never been asked to weigh my carry-on. For a short period of time last year they tried to measure the size of your luggage... but they seem to have stopped it.

Dashes - the rules are less strict than on ATRs, but still some passengers are asked to leave their stuff on the trolley before the boarding.