From ServiceM8 9.1.1, it's possible to subscribe to a plan through the ServiceM8 app, via In-App Purchase. This offers a convenient, central and mobile-first experience to manage a ServiceM8 subscription.
The app supports the option to subscribe to a Lite, Starter or Growing plan via In-App Purchase, available in More > Settings > ServiceM8 Account.
The subscription is an Apple Subscription and charged to the credit card attached to the Apple ID used to create the account. This type of ServiceM8 subscription can only be managed through the subscriber's Apple ID (including upgrading, downgrading or cancelling the subscription).