No, you don't. It is is possible to use the app anonymously. When the app starts, you are required to login, create an account or continue anonymously. If you choose the last option, you will proceed to the main screen of the app and you can use it in the same way as when you would be a registered user.
The option to "Continue anonymously" is on the bottom of the screen.
 | When you do not create an account, you are not able to use it on multiple devices or recover your data when you need to restore/lost your phone. You will be able to change your anonymous account to a registered account via the Account menu. |