For apps there are is only one possibility to start a subscription:
If Google Play Store asks you before you download an app if you want to purchase an app for a certain amount of money, then this is an one-time fee. To my knowledge apps can only have a one-time-fee or they are free (to be downloaded).
Repeatable fees are are usually billed as in-app-purchase. That means you open the app and at some point the app can ask you if you want to start a subscription. That will open a Google Play dialog containing the price, when the subscription starts and so on.
in-app-purchase can also be a one-time payment. But that is then visible in the Google Play payment dialog.
Active subscriptions can be viewed in Google Play Store app in section Payments and Subscriptions. The same is possible in the web interface which also has a section Payment and Subscriptions