For Pay a Visit?

: to go somewhere to spend time with (someone, such as a friend or relative) : to visit He paid a visit to his parents.

What is the difference between visit and pay a visit?

"Visit" can be used with something routine or commonplace. "Pay a visit" tends to refer to something out of the ordinary.

Is it payed a visit or paid a visit?

The correct past tense of the verb pay is paid, as long as the word is used in the financial or transactional sense. If the verb pay is used in a nautical sense, the correct form is payed.