After the potential expiration date of the scores you directly received from publishers in Newzik, all the work you brought to the work will remain yours (markings, cuts, enhancements), but the sheet music will be covered with a blue watermark. This watermark can be removed by recontacting the publisher for a new rental: the scores will be in the same state as right before the expiration, will all your previous changes saved and ready for you to continue working on the music.
The publisher does not receive or see any of your markings, cuts etc.
You can still see, select and copy-paste your markings underneath the watermark, if you want to paste them in another Piece in Newzik that you own, under your own responsibility.