must–have 
/ˈmʌstˌhæv/ noun
plural must–haves /ˈmʌstˌhæv/ noun [count] chiefly US, informal : something that is necessary to have or get
▪ The newest version of the software is a must-have.
▪ The newest version of the software is a must-have.
— must–have adjective always used before a noun
▪ must-have software ▪ a must-have accessory
▪ must-have software ▪ a must-have accessory
