(adsbygoogle = window.adsbygoogle || []).push({}); Here is what I Am looking to do

Login - Username / Key(I Can do)
If key is invalid prompt user to buy
but from there I don't know where to go from the buy part? Paypal SDK? I'm not even sure...
Now I'm not actually looking to sell anything btw here guys I just want to learn for future (again not looking to sell nothing)

I've got a database and stuff but the payment part I don't even know where to start.

If anyone has any sources, tips or anything but yeah.

Use Betterseal.Net, its very little coding involved in C#, when you make an account you can gen 10 keys for 5 programs. then you have to purchase more. but its very cheap, easy to use and its an amazing net seal

Yeah I agree, use betterseal I paid £5 for 50 licenses so it's really cheap aswell

Look into a ipn via paypal or btc. There is.

Requirements:
Server with php, html, mysql

Github has a simple example and if you add me over skype ill give you a class i made ages ago and can assist you with setting it up.

Skype: hacking2471
The one that says: 'MFA Sleeping JavaCodeLLC akaMeltDown'.

Try betterseal or why not pm me Iv got a hwid system that logs their ip and hwid to a sql database

Why not try and make an API to your server that you are hosting on and receive and post requests from each side using auth keys ? It's not hard making your own SDK.

Why do that when you can use tustins custom Auth which is so much easier

Some people do it for experience and don't like depending on others for software.

yeah i get where your coming from, im attempting to my my own custom auth