Where can i fine the cvv number ? Is there any expiry date for my verified paypal account ? Do i need to verify the paypal account again with the same credit card ?
You can see the image below to know what is CVV number. Basically it's the three digit number which you find in your credit card.

https://www.asprs.org/application/cvvnumber.htm

As I already said, make sure you have at least $1.95 in your credit card, otherwise you can't verify your PP. Once you verified your account, it will remain verified account forever, no matter if the credit card is expired or not.