Hi, as long as you don't give them free access to the entire SFX pack, it should be fine.
Viewing post in Retro RPG 100 UI Sound Effects comments
Hello, the way it basically works is, I need to give a license to the customer, this license contains details about how they are able to use the source code, Also, copyrighted material, such as shutterstock media, copyrighted assets, all of which will not be included in the source files - However, they will be included in the project’s files, which is something you can’t easily access without a copy of the game engine. These are also not typically in the original format that the original asset was in, for example, it may be resized, compressed, or even modified. We would only ever give them access to the compressed, modified content, and not the original content that I obtain from say, itch.io.