Yes, you can re-download your purchases at any point.
To do this:
Go to www.qobuz.com
Click on your name on the top right of the screen
Click on “My profile”
In the “My Purchases” tab
Click on “Access Download” link next to the item(s) in question
Please note: The albums may no longer be available for download, which is why we recommend to users to make a backup of their purchase.
I haven’t found an answer to my question: contact our customer service team.