In 1656 he was granted a royal license to open a pharmacy in Nykøbing Falster (Løbe Apotek).
In 1660 he obtained a royal license to open Svane Apotek in Copenhagen and ceded his pharmacies in Nykøbing and Nakskov to two son-in-laws.
Herbarium Danicum sempervivum, a collection of painted illustrations of 140 plants created at Heerfordt's initiative by two foreign artists, is now kept by the Royal Danish Library.
Herbarium was also involved in the collection of material for Peder Lauridsen Kylling's Viridarium Danicum from 1670.
He also sponsored the posthumous publication of Anders Arrebo's left sermons, Torcular Christi.