update local database

Description

Hi Sorry for basic question but if I have created a subscription button either from using the wizard or coding with curl how am I meant to update my local database after a successful transaction? There are plenty examples online but they all use the PayPal v1 SDK which I dont think I can use as its being deprecated am I meant to do it with web hooks as when I try to call a function imbedded in the PayPal button onApprove it just hides the button or just does not fire so I assume im trying an illegal path