We manage a client's web application, including all maintenance and feature enhancements, on their behalf. It is used through their entire organization by staff to process licensing applications from individuals worldwide.
I inherited Laravel projects originally created by other developers. I haven't migrated clients at this time, however as the project gets bigger and I need to find more elaborate workarounds to address needs that option will be put on the table.
I've implemented Lumen for some basic system automation and it would be fine for a basic API implementation (though there are still better options). In general, if you are working with a system that has a complex database structure and potentially complex querying requirements, Laravel is not the right choice.