I am fairly new to PHP (about 8 months). I am building a web app, which is almost ready for beta. I am only now starting to think about what I would need to do to make a mob
Not necessarily, you don't really need a framework for anything! The framework is made just to provide you with tools to help building your projects faster. These days in most cases it is smarter to use a framework, cause who likes to reinvent the wheel!
Since you are a PHP developer and the best answer suggests to take a look Laravel, I would also suggest that you to take a look at Apiato (apiato.io), this is a PHP API framework built on top of Laravel. It lets you create your API way faster than starting with a vanilla Laravel, as it provides you with tens of features that you already need for every API.