Google’s John Mueller long before said to keep your redirects active for over a year. He said, “It can take 6-months to a year for Google to fully recognize a site has moved. Plus, you may have people finding old links, and if those no longer have redirects, they may lead to a 404 page or a parked domain, which would result in a bad user experience.”

Some people at that time opposed it, and some agreed. They were all discussing its goods and flaws. On Sep 11, 2015, they Live Streamed the entire discussion about the incident.
John later added that it should be “at least one year,” not around a year. So that you can ensure that the redirects are “reprocessed a few times.” He said that most of the time, redirects are left in place for years.
See also: How Redirecting URLs Can Impact SEO?
Contents
John Mueller’s Tweet To Keep Redirects Active For One Year
Here is what John tweeted
I’d usually try to keep redirects in place for as long as possible, at least for a year, so it’s been reprocessed a few times. In practice, they often remain in place for multiple years.
Users replied and asked, “What if the old domain is no longer registered? Also, how long do we need to keep those redirects? Can we remove them after one year?”
John then replied and explained.
“Usually, if the domain registration drops, then you can’t do anything like redirects. This is one of the reasons why we recommend keeping domains registered for a longer time, even when moving.”
How Google Works On Redirected Links
Gary Illyes used the word “concrete answer” when he gathered knowledge about how Google works itself. He says that you have to keep your redirects active for “at least one year.”
This will end up in signals that will pass from the origin URL(A) to the destination URL(B) till the time google finds out about the redirect and when Google notices the URL is removed.

This indirectly means that the signals from the origin URL are being passed to the destination URL will be connected with the destination URL even after removing it. But after removing, the signals will be going to the Origin URL, not the destination URL.
Gary’s Announcement
Here is Gary’s announcement on this discussion
“Hands up, if you asked us recently for how long you should keep redirects in place! I have a concrete answer now: at least one year. (but try keeping them indefinitely if you can for your users).”
It’s Google’s first time that they have officially confirmed that the signals passed through redirects last forever, even after the redirect is removed or moved. That is if you keep your redirects active for atleast one year.
You might also want to see: Redirects and Google Search
Final Words
Google is launching updates back to back, there is a possibility that some correction, later on, pops up in this topic, and something changes. A lot of updates of different kinds are being processed. You just have to wait and see what Google has for you now. We know that Google won’t do something that affects users in a bad way.