Suppose someone has a coupon for a free [let's say, iced coffee] from a store. What are the problems with getting such an item from the store, on Shabbos (or Yom Tov)?
To boil it down to more general problems, let's assume:
- there's no problem of carrying (e.g. item will be consumed in the store, or there's an eiruv)
- the store is owned by gentiles
- the employee who will be servicing is a gentile