Not sure where to put this, or if anyone knows this, but If you have bought a second-hand/used 3DS/2DS console and have A9LH installed on it,
get Decrypt9WIP setup and dump your Titlekeys (using TitleKey Options > TitleKey Dump (SysNAND)) then decrypt them (TitleKey Decrypt (File)
and then upload the decTitleKeys.bin file to that Titlekeys site (even if you have never bought anything on the eShop on that console.)
.
It appears that even if the console is formatted, the Titlekey data remains in the TicketDB of the 3DS (although the tickets are probably marked as deleted?)
Seems those Titlekeys are readable by Decrypt9WIP. I've installed A9LH on a few used 3DS consoles (systems had no games installed and appeared to be freshly system formatted)
and managed to pull a few titlekeys for full games (and some demos too) which I assume the previous owners had purchased/downloaded off the eshop.
(Sadly, all the Titlekeys I got were already in the database, but its worth a try, your 3DS might have a few keys that the database doesn't have yet.)
(edit: Its probably best to do this just after you install A9LH (before you install any CIA file)
if the ticket data is marked as deleted, the 3DS might overwrite titlekeys when you install a game)