As far as oaths of fealty go, no, there is no hard and fast pledge that I know of. Consider that random folks becoming lords is basically not a thing in Westeros, except on very rare occasions. The two oaths I know of in Westerosi lore are that of the Night's Watch, and the Seven-based ceremony involved in knighthood, neither of which are particularly applicable.
There are a couple of commoners throughout the story that become lords, and the general practice there seems to be the king, queen, or regent saying, "Hey, you're a lord," and granting them an unoccupied fief as a seat.
What Thane is obviously referring to are the titles that specific rulers have bestowed upon them, which is, obviously, irrelevant.