Please keep in mind that although I'm incredibly lucky to be able to do what I do and love it passionately, I still have to make a living doing this. There are bills to be paid, tacos to be eaten, and guitars to be bought. I am in the business of selling my time, so in addition to the knowledge you will be receiving; the time in which it is received is also of value.
To know in advance you that won't be coming allows me to free up the slot you have booked to teach another lesson (making extra money is good for people), grab something to eat (sometimes I have to teach 6-8 hours straight, and I can't really explain melodic minor harmony with a mouthful of burrito); or just get focused and practice for a while not worrying about whether or not I'll have to start teaching a lesson at a moment's notice.
You will be permitted one cancellation per calendar month provided that notice is given before 24 hours of when your lesson is scheduled to occur. In short, you can't cancel within 24 hours of your lesson, otherwise you will be charged. You can do this once a month.
If you cancel a second lesson, even with 24 hours notice, in the same month as a previous cancellation you will forfeit payment for that lesson.
Failure to appear for a scheduled lesson will result in forfeiture of payment for that lesson.