As soon as you have started your subscription and when the payment has gone through you will receive a receipt sent to the e-mail address you have created your account with.
You should bear in mind that the email with the receipt can get stuck in your spam folder, so don't forget to check there.
A new receipt will not be sent when your subscription is renewed, but you can always see them under "Subscriptions" on your profile.
When you cancel your subscription, you will receive a receipt with confirmation sent to you. If you have not received this, your subscription has not been terminated or this email may be in your spam folder.