Does anyone do this in their school?

Apparently it's the way a lot of yoga teachers sell their time here in AVL.

I've been approached about it for private lessons and am trying to figure the pros and cons of it.

One thing I've thought of is that there should be a term limit on the card, should there not? As in: If someone buys 4-8 private lessons I would expect them to take/redeem them within....1-3 months ????

Thoughts?