I have one active playlist which contains about 50 songs. But I remove and add songs very commonly at this playlist. I want to have another playlist that includes all song that currently are and have been in the active playlist. Can someone help me to create that smart playlist?
iTunes' Smart Playlist feature does not have any memory. You can only refer to songs where/how they are in this very moment.
You can, however, add songs to the new smart playlist that have been played in the last X hours/days.
If you can 'explain' to iTunes how to find the songs that you want to have included/excluded, you can create a smart playlist for it.
Does this answer your question?