How to get response from Unsubscribe button from Paypal

Hello All,

I am trying to use paypal's unsubscribe button in my website. Below is the format of that button.

Now My Requirement is, Once it is unsubscribed successfully, i want to make entry for that specific user in Database.

Can anyone please help me how can i implement this scenario ?

I am familier with adding entry in database but i am confused about logic how to get success response from above mentioned link.

I have gone through many tutorial but not finding any right approach to implement this.

Thank you in Advance.