Each designer allows different things. Some consider S4H S4O as ok in PU, Some do not and they consider it Commercial Use.
Usually the TOU has an email address that you can use to get a hold of the designer
And just beware, the kits that are made of photographed items, if the photograph of one (or more) of the elements is a copyrighted item, (such as Crayola Crayons or someone's sculpture or a Ferrari) you can be sued for using it.
Just because the "Designer" cut out a picture of it and put it in their kit, and hasn't gotten caught yet, does not mean it is legal.