A licensed piano tuner? Who licenses them? Where do you apply for these licenses? What local, state, or Federal department oversees the licensing?
Jokes aside, you can register as a Piano Technician only “after a series of rigorous examinations that test skill in piano tuning, regulation and repair. Those capable of performing these tasks up to a recognized worldwide standard receive the RPT credential.” (cite)
So, yes: You can be a credentialed piano technician, licenced by the PTG, only after testing. As for your last question, well, that’s just silly.
Done it. I have a little red doohickey I blow through that produces perfect pitch on all 13. \\
The finer points, e.g., making sure each key is in desirable accord with other keys, and playing very fine games with the overtones between each of the 3 strings, etc, is beyond me, but I doubt that one professional tuner in 10.000 does any of that anyhow. They just bring the strings up to pitch and look for broken parts to tell you about.
Almost. There’s very different levels of credentials, and some of them are near to meaningless.
A “Registered” anything means a professional organization has them on a list. It usually, but not always, means that they have some verifiable training in the field. It often means they hold liability insurance, because many professional organizations supply that as a perk of membership, but this totally depends on the organization. So become a member of the PTG, and you’re Registered, but not Licensed.
A “Certified” anything means you went to school and got a Certificate of Completion (based on attendance hours) or a Certificate of Achievement (based on test scores- not only do you have to show up, you have to pass a test) or a Certificate of Merit (based on anything the school wants to, but usually bullshit.)
A “Licensed” person holds a license from a governmental agency - federal, city, state or county. Some licenses are granted after a fee is paid, others after educational requirements are made, tests passed and a fee is paid. A license in one state does not automatically give you a license in another state. License requirements for the same field in one state may be very different than the requirements in another state. Generally speaking, if such a license exists in the area, a non-licensed person is not legally allowed to do the job.
So a Certified Piano Tuner may have taken a weekend course at the park district, or have studied the care and feeding of pianos for years. A Registered Piano Tuner passed the Piano Technician’s Guild test. A Licensed Piano Tuner is recognized by some governmental branch as a Piano Tuner, but depending on the area may have a lot of training or none at all.
Illinois, at least, does not license piano tuners, so it’s a moo point. 
But I’m just sayin…
All the information in this post adapted from what I learned forming and running a massage therapy school (thus certifying graduates) during the era when Illinois began licensing massage therapists and numerous professional massage organizations began doing business.
Ask me about the difference between “State-Approved” and “Accredited” schools sometime. On second thought, don’t.
How much tuning does it need? Remember that for many of the notes you have three strings to tune. Not only will you need a hammer, but you’ll need felt strips and some rubber wedges.
The advice given thus far is good, but if the instrument is definitely out of tune, and individual notes are out of tune with themselves as well as the rest of the instrument, it will be so worth your while to pay someone. I don’t know what the going rate is where you are; here I get a very quality tuning for about $85. I have a hammer and tools to do minor touch-ups when needed, but an instrument that’s really out will be probably cause more frustration than it’s worth to do yourself.
The issue here is that this piano is hours away from civilization. We’d have to pay serious money to anyone just to make the drive, let alone tune the piano. If it was in my living room, it would be done.
Also, I now hear this is an instrument the owner is thinking of getting rid of anyway for pennies on the dollar, if not zero pennies on the dollar. So, if there was ever a time for me to fiddle around with the idea, that time is now.
You’re going to this cabin to write songs, so why waste your time tuning a piano? What is everyone else going to be doing while you’re doing this?
I’m getting there a couple days early to meet the owners (Birdgirl’s family), set up some recording equipment, learn about septic tank maintainance, those weird swampy heater things, and other stuff city boys are ignorant about.