Authorize is the opposite of Prohibit. Prohibit is the opposite of Let. Let is related to Hang. Hang is related to Club. 
Ought is related to Must. Must is a synonym of Requirement. Requirement is related to Demand. Demand is related to Economics. 
Authorize <--Antonym--> Prohibit <--Antonym--> Let <--RelatedTo--> Hang <--RelatedTo--> Club 
Ought <--RelatedTo--> Must <--Synonym--> Requirement <--RelatedTo--> Demand <--RelatedTo--> Economics 