The following information is regarding TuneCore's Publishing Administration service
It is sometimes possible to collect previously unclaimed royalties. However, it’s not quite as easy as collecting royalties from the point that your compositions are correctly registered at the global performing and mechanical rights societies.
How successful this process is will depend on the rules and systems in place at the societies and the digital stores and streaming services, and the time that has passed since the original use. All that being said, it is not unheard of for unclaimed royalties from uses up to three years ago being recovered.