At what age do people forget how to use teleportation?

About 5 years old (give or take child's height and weight). The faster a child grows, the quicker the power is lost.

At the age when you are too big to be carried by mom and dad, and they wake you up and make you walk to your room.

I think it's much older than that.

I can remember nights when I've been at the pub, and the next thing I know I'm in my bed and it's the next morning.

Don't know how that happened!

At least it was your own.

I totally agree with that! It even happened when I was in my 30's, though I wasn't quite in doing it, since it was a bed in the hospital.

I remember once, when I was in my late teens, one minute being on a pub crawl around Richmond, then waking up in a houseboat on the Thames with a very interesting older lady cooking breakfast in the galley.

I wish I could remember more, really.

It was in 1970, during my time as a conscript in the navy. We were two months in France, and stayed for a couple of days in La Pallice (La Rochelle's port).
That was very frustrating after two weeks in Biarritz and Arcachon. So, we mainly stayed in the local bars and played cards there. One day, I had quite a bit of luck ... and trebled my "salary". When trying to get some sleep afterwards, I was woken up and ask to join a couple of seamen to a casino. (They had been invited by a local businessman.)
I remember that we had a nice time in the casino.
I woke up on a pontoon, 12 meters below the quay, attached just by chains, on the opposite side of the basin where my boat was, about one nautical mile away ... But I could hear "· − − ·", saw the Blue Peter and the funnel smoke ... running, running ...
Fortunately, "The chief" had somehow "lost" both his peaked caps and waited for me to do some translations. I could exchange them against two crates of Pilsner Urquell.

No-one could tell me, how I arrived there (it certainly must have been during high tide, so I could narrow the time).

Reminds me of a trauma I reported here a while back:

http://able2know.org/topic/51508-1

Yep, that was lucky.

That was great.

Hope you recovered okay.