Create a Simple SAAS platform that will allow this features below:
(you may try any free trial SAAS ready app to understand)
However here's some explanation:
a) Dump apps in a folder where by when user creates an accounts and upon account activation the app will automatically install on a subdomain if sub-url is available (eg; http://yourusername.appname.com)
b) User to create group with same validity period of main user (admin to control for enabling or disabling based on app and discretion of direction/ plan)
c) Paypal integration and documentation for other gateway to be integrated
d) Report for app, admin and users
e) User & Admin Management
f) User & Admin Dashboard
g) Auto reminder on account expiry
h) and anything else that i missed here will be in documentation.
Thank you for your interest.