A Lumen app that will act as API endpoints. The main purpose of this project will be to accept the requests, do minimal processing and throw a job in the queue.
A Laravel app that will contain all your business logic and domain-specific code. This project will be listening to the jobs pushed in queue by the Lumen project and will process those.
@mohitmamoria The Lumen API would have some classes (Repositories, Observers, etc.), so in the Laravel Project I would be able to use those classes as well, so I will have to mantain only the Lumen API.
More than API I would call a "package" based on Lumen.