I restore my purchases and next day I have to restore them again. Any idea as to why this is happening? This has happened twice now.
Outside of a bug, the most probable cause is that somehow you are switching your brush library. For example, if you cannot find your brushes, open the brush selector near the top, it should tell you what your currently selected library is. Mine is on Painter 2020. If I select a different library, for example the "Natural media brushes" library, my brush purchases won't be in there. But if I restore them, and switch back to the Painter 2020 library, they should be there.