He probably sold his first maps from a stall in various places in London. From 1688 he had his own shop in Vanley's Court in London's Blackfriars. Between 1691 and 1710 his business was located at the corner of Spring Gardens and Charing Cross, and he finally moved along the River Thames to Beech Street where he remained until his death.
In the 1690s, Moll worked mainly as an engraver for Christopher Browne, Robert Morden and Lea, in whose business he was also involved. During this time he also published his first major independent work, the Thesaurus Geographicus. The success of this work likely influenced his decision to start publishing his own maps.
This confirmed me in the opinion I have long entertained, that the maps and charts place this country at least three degrees more to the east than it really is; which thought I communicated many years ago to my worthy friend, Mr. Herman Moll, and gave him my reasons for it, although he has rather chosen to follow other authors.
Jonathan Swift. Gulliver's Travels Into Several Remote Regions of the World (1726)