Avoid In-App-Purchase for Core Web application

I have an app that is completely web app with monthly subscription. The web app have free Android and iOS apps that are free. But to use them, you need active subscription on the web. Reading Apple's guideline 3.1.1 > If you want to unlock features or functionality within your app, (by > way of example: subscriptions, in-game currencies, game levels, access > to premium content, or unlocking a full version), you must use in-app > purchase. **Apps may not use their own mechanisms to unlock content or > functionality**, such as license keys, augmented reality markers, QR > codes, cryptocurrencies and cryptocurrency wallets, etc. As far as I understand it, it means no unlocking via app itself, but is fine using web app to do so. Am I correct? Will showing users "Your subscription on your Business account have expired. Please contact your business administrator for renewal" on let us say a modal dialog and clicking "OK" Exits the app be okay? I think it is not clear and if not there yet, Apple should clarify how SaaS with mobile add on should work. If it is already somewhere, I would appreciate someone linking it.