Hi there.
So from what I understand, you paid for the Cleanup product sepperately without an Avast Premium security licence or any other product? Because if so there hasn't been a lot of info about that, but I am quite confident that if you have an Avast Premium security subscribtion which is a single device one you will be able to migrate sooner or later, well maybe you already can. The multi-device one still does not work.
Hope this helped at least a little!