Expiration time of a trade website query link

Hello.

I experienced in the past that some of my old search links stopped working.
I mean links like this:
https://www.pathofexile.com/trade/search/Necropolis/L3L7DEjhn

Explanation I was given - these queries are getting delited after 3-4 months of not being used.

So in order to make sure my saved queries are working, once in ~75 days I open each of them.

Could I get an offitial answer on how many days does it tako for such query to expire after the last time it was used?

Good to know.
Thank you!