It’s usually 5-10 years depending on country, though almost all countries allow you to file for an early judicial declaration of death to potentially speed things up.

Though even then don’t really count on life insurance, which almost always has separate clauses for the type of death which would be impossible to prove if there’s no body. Extremely few insurance types pay out for missing people, since it’s a legal and PR nightmare for the company if that person shows up again.