The first place to look would be in your email inbox. All receipts are automatically sent there. (You can search "BetterWorld" or "[email protected]").

The second place you can find receipts is in the My Account area. Head to My Account, and click on the Giveaways tab.

Note: It's always possible -- if you didn't receive an email -- that there was a typo in the email you signed up with. You can double-check this by heading to Settings, and scrolling down to see the email address associated with your account. You can change or update it there if you like!