You could invoke MATLAB from PHP, or use PHP to communicate through the MATLAB Engine interface. If you do that and the resulting program is accessible to the outside world, then you need the most expensive form of MATLAB license to access MATLAB itself this way.
You could use MATLAB Compiler SDK to create something that can be invoked by a web page. This would create an interface that relied on the MATLAB Compiler Runtime (MCR) but did not require a MATLAB license to run.
