You’ll receive a confirmation email, and your subscription details will be stored in your account settings. 

You can also check on your Apple ID or Google Play's subscription settings. 

• iOS (Apple ID): Go to Settings > tap your name > Subscriptions.
  
  
• Android (Google Play): Open the Google Play Store > Profile > Payments & Subscriptions > Subscriptions.

For more details, visit the official guides: Apple or Google Play