This is the 14013th most frequent Russian word.
обязательную
Mandatory.
The word 'обязательную' is used as an adjective modifying 'меру', meaning 'mandatory' or 'compulsory', emphasizing that the measure is required.
Мы приняли обязательную меру для защиты населения.
We adopted a mandatory measure to protect the population.
'Обязательную' here describes 'школьную форму', meaning that wearing the uniforms is a requirement imposed by the school.
Эта школа имеет обязательную школьную форму, которую должны носить дети.
This school has mandatory uniforms that the children must wear.
The word 'обязательной' modifies 'процедуры', indicating that the licensing procedure is compulsory as per the law.