I haven't yet lol but I think eventually its recommended

You have to eventually. But not till very late in the game.

I would keep it until 100 Lock-picking, then give it back. You have to give it back eventually to continue the quest line.

Do what tricep said, just keep using it until you have 100 lockpicking, then get the "Unbreakable" perk. Once you return it, you will be able to pick one of three special abilities from Nocturnal.

Halo_4 wrote Do what tricep said, just keep using it until you have 100 lockpicking, then get the "Unbreakable" perk. Once you return it, you will be able to pick one of three special abilities from Nocturnal.

Yeah, I agree. This is the best thing to do

Dont worry about it bro give it back and then just mod your gamesave via Pc Skyrim

Skeleton Key for lock pick increase is not good. It is unbreakable when you can easily acquire lock picks. When they break the skill goes up and when you open it the skill increases significantly. Without that modifier the skill increases slower.

There's really not point on delaying the Thieves Guild quest just to level lock picking honestly. Lock picking isn't that special unless you absolutely suck at picking locks. Just give the skeleton key back, because the Thieves Guild completed is far more better.

I usually buy like 100-200 lock picks. They aren't expensive and they last me a LONG TIME.

Like above poster said Thieves guild="far mo better"