Convert standalone web app to SaaS / multi-tenant application

The current web application is a standalone application. We setup the web app manually for every customer. We would like to convert the standalone web app into SaaS structure (or multi-tenant) application to accommodate unlimited customers. Priority Modules: * Subscription model - Customer selects the features/modules of the software and accordingly makes payments. * Payment plan management - Per user or team. Payment frequency will be monthly/quarterly/semi-annual/annually. * Payment methods management - adding payment gateways * Pricing plan management - Includes all the pricing plans offered, trial period management, enterprise plans for customers with custom requirements * Enterprise plan - This is for customers with custom requirements. The payment methods offered will be wire transfer, bank cheques etc. * Customer management - Customer signs up from website (eg. [login to view URL]). Creates an account and sets up domain name ([login to view URL]). All company users can login from company domain ([login to view URL]) or website ([login to view URL]) * User Management - user privileges and permissions, add user groups and roles Technology Preferences: - LAMP Stack (PHP), - Laravel PHP framework, - MySQL/PostgreSQL Propose the following: 1. SaaS System Architecture 2. Cloud Server to be used and the proposed server architecture 3. Timeframe for development completion