Organic nomenclature of substituted diamines
According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), superscript arabic numbers are used to differentiate the nitrogen atoms.


  P-16.9.2 Superscript arabic numbers, which are the locants of the parent structure, are used to differentiate the nitrogen atoms of di- and polyamines, di- and polyimines, di- and polyamides, except for geminal amines, imines, and amides.


In particular, note that the superscript arabic numbers correspond to the locants of the parent structure. Since the parent structure of the compound that is given in the question is pent-4-ene-1,3-diamine, the locants are 1 and 3. Therefore, the complete name for the substituted compound is N1,N3,N3-trimethylpent-4-ene-1,3-diamine.