Mine sold for 20 but was double spelled so probably shouldn’t be used.

Few more sales:

https://backpack.tf/item/714580792

https://backpack.tf/item/1347183799

https://backpack.tf/profiles/76561198135221428#!/compare/1610928000/1611014400 - 6 Keys match

https://backpack.tf/profiles/76561198811544015#!/compare/1610928000/1611100800 - Bought and sold for 12 Keys

https://backpack.tf/profiles/76561198799648359#!/compare/1611187200/1611273600 - Sold for 13 Keys

https://backpack.tf/profiles/76561198175597329#!/compare/1611273600/1611446400 - 1 of the 13 Keys are here

https://backpack.tf/profiles/76561198078061600 - The other 12 were for the Private Eye in the 1 of 13 link

https://bot.tf/stats/listings/MXED9V81 - One was listed for 12, but this sale isn't traceable

https://backpack.tf/item/3547217119

https://backpack.tf/profiles/76561198841279602#!/compare/1608940800/1609027200

With 2 sales at 12 and a third likely sale at 12, I'd go 12 - 13, even with buyers at 12, for a more conservative raise.