Yes. This is done using an anonymous ID that you yourself have the key to in the app. This way, we ensure that you do not have to start all over again if you delete and reinstall the app.
Have you lost your progress? This can only happen if you log in through another system. Even if you delete the app, your progress should be saved. For example: the first time you logged into the app you used your email, but another time you used your Apple ID instead. Every time you log in through a new system, an anonymous ID is generated in our database, so the app views you as a new user. Check to see if you have logged in using a different method, and if that does not help, please contact our support team (firstname.lastname@example.org) and we will do our best to restore your progress.