Ha, I read the title and thought you were talking of something else
The launcher contains the code for the protocol. It knows how to accept requests for data and to send the requests to the SAFE network.
APPs do not natively talk on the SAFE network, or any other either. But like most programs running on your computer they (via library code often) make api calls to the underlying operating system or other program to have some task performed. EG C code writes to the disk via library code that is linked in at compile time and that code does api calls to linux (or windoze etc) to do the writes.
So SAFE APPs will do api calls to the launcher to access the SAFE network.
To answer your question, like @wes says, the launcher will be program that is loaded once and remains in the background accepting api calls and accessing the SAFE network to perform the task requested.
Just to say it what I thought you were meaning was more to do with how the launcher will look in the future and if maybe it will be a library that is linked into APPs, but this then requires the APP to be re-compiled with each launcher code update. With them being separate then ONLY if the api changes then maybe the APP needs recompiling if the changes to the api affect it.
Another thing that has been tossed around a (very) little is the idea that all SAFE APPs will run in a thin virtual machine which most likely be the launcher. That way more protections for the user’s machine could be implemented.