If this content is totally duplicate and they already have theirs indexed (with a bigger site), you'll want to keep these as "noindex, follow" with your meta robots tag. But, one of you should be the "owner" of that content and keep it indexed, not both of you. That will depend on A) who actually created the content and B) who should own the content and traffic. When your rev share expires, whoever gets to keep the content should be the one that has it indexed.

You also have the option of telling Google not to crawl these pages using your robots.txt file. The downside to this is that noindexed content can still pass link value to other pages of your website, but not if they can't crawl the noindexed pages. The upside to this is that it gives Google more time to crawl your other webpages which are actually indexed. This is related to the concepts of crawl budget (how much Google is willing to crawl your site over a time period) and crawl prioritization (making sure they crawl the good stuff).