Payment gateways handle subscription but we can treat a final purchase like a subscription with our own system, and to use gateways subs, for that you need to use their sdk and new updates one after one or it will be complicated when implementing their API for expiry etc. in app. The extension serves Global solution for any payment gateway. If any person is maliciously hacking your database (for example spreadsheet) then use 2 database one having READ+WRITE enabled for new onboarding where payment done and newDate is stored and 2nd one as READ ONLY database which is used to count days and validate subscription, if one follows this no body can modify it and server cost can be saved. Extension is very useful for them who are getting online date and have their own way of providing subscriptions. Hope you get the point.