BKEX Grin deposit, WTF is a MEMO?

I wonder how long the memo system is in use by Gate.io and others.
Would it be due to this ‘online bookkeeping’ idea I started in in April 2021 :sweat_smile:, or would it predate it.
[Withdrewed] Request for Funding @davidtavarez: One-time use Slatepack addresses for Wallet (RFC and Grin++ Implementation) - #33 by Anynomous

Update: Thank god, I am not guilty of that.
It dates back to at least 2019: