Web version:
1. Tap the person icon.
2. Select Account > Email Notification Settings.
3. Your registered email address will be displayed on the next screen.
App version:
1. Tap Profile on the bottom menu bar.
2. Tap the gear icon on the top right.
3. Tap Settings.
4. Your registered email address will be displayed on the next screen.
Related:
I want to change my registered email address.