Source : Webster's Revised Unabridged Dictionary (1913)

Therefor \There*for"\, adv. [There + for. Cf. {Therefore}.]
   For that, or this; for it.

         With certain officers ordained therefore. --Chaucer.

Source : WordNet®

therefor
     adv : (in formal usage, especially legal usage) for that or for
           it; "ordering goods and enclosing payment therefor"; "a
           refund therefor"