How do I find what in app purchases I made

I purchased the app Naturespace a while back. I have made in app purchases of tracks, but when I got my new phone I am having trouble restoring those purchases. I want to be sure that I am getting all the tracks I purchased but I can't remember them all. Is there a way to find out what tracks I should have. Naturespace folks have been great. I am told I need to check my purchase history. I may have all the tracks I purchased but I am not sure. Is there a way to find out? Thanks