follow up bi bilo dalje praćenje, evaluacija, naknadne aktivnosti nakon što je nešto urađeno.

U ovom slučaju, reč je o idiomu "follow up with" http://idioms.thefreedictionary.com/follow up with koji znači "to continue talking to or working with someone", konkretno - praćenje kupaca, naknadne komunikacije (održavanje komunikacije; kontakata; saradnje sa kupcima).. što bi u principu značilo da oni teže da, nakon što reše upite kupaca, da ih naknadno kontaktiraju da ih pitaju da li je sve u redu... nastavljaju da "prate" svoje kupce (odnosno njihove potrebe)

http://www.morebusiness.com/customer-follow-up
Following up with customers is just as important as convincing them to purchase your products and services.
Try Different Methods of Routine Business Follow Up
You can follow up with customers using different methods of contact such as e-mail, sending postcards, flyers or greeting cards, or by simply using the telephone.
...When it comes to following up with your customers, it pays to be consistent. This way, you ensure that your name and that of your business is always in the forefront of a customers’ mind.