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It is true that the system is set up to payout in seven days, and once that happens, the post can no longer generate income.

However, there have been attempts to extend the life of a post. I know of two, but there may have been more.

The first is called the Dead Post Initiative. I believe the idea was to republish a previous post with a hashtag designated as part of the dead post initiative. Then, those who went through the hashtag could read it and upvote the repost if they so chose.

However, there were some users who frowned upon the practice, and started flagging some of the content. I'm not sure if that led to its demise, or if there were other factors, but it appears its been three months since any official post from one of the users involved, and I could no longer find new posts under any related hashtags.

The second one is newer, and is called STEEM Forever. The user behind it is knircky, the same person who created STEEM Bounty.

The idea is to go to the STEEM Forever website, paste in the URL of the post you would like to keep earning, and it gets a comment placed on that people can upvote. My understanding is knircky has kept some of the upvote as a fee for use.

For more information, try looking up past posts by knircky about STEEM Forever. The website itself is a little light on information.

As suggested in another answer, it is possible to continue to comment on a post beyond the seven days in hopes of receiving upvotes for those comments. I doubt that happens very often, but it's certainly something to try.

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