It's probably just an issue with your namespace.

Check out this example to help you pinpoint the issue:

location: app/PurpleGriffin/ELearningCourses

namespace App\PurpleGriffin\ELearningCourses;

class ELearningCoursesClass {
      public function convertPrice(){
              //convert that price here yo
      }
}

location: app/controllers

namespace App\Controllers;

use App\PurpleGriffin\ELearningCourses\ELearningCoursesClass;

class CoursesController {

    public function getCourse()
    {
        $course = new ELearningCoursesClass();
    }
}

Remember, you should call them from the root namespace. e.g:

 $classVar = new class(); will become $classVar = new \class(); 

after all is said and done, you need to run your composer dump-autoload to get everything recognized.

Let me know if this helps.