S3 faces working on Watch 4?

I’m assuming that the watch faces I purchased for the S3 will not work on the Watch 4. If the developer makes the changes can they be transferred over or will I have to buy again?

A face Facer face that works on any watch will work on every watch that supports Facer. The Galaxy watch 4 it’s one of those. No change needs to be made to any individual faces.