Here's what I'm trying to do:

Basically, I'm trying to make an arcade site where you pay upfront from Paypal. So the user can go in and buy a month membership to use play games on the arcade console which expires at the end on the month in which the user would have to pay again at the beginning on the month. (I don't do that automatic withdrawl stuff.) Now what happens when the user pays is that their IP address gets added to a database and they can play games. (I have a policy of games running only on one machine at a time to avoid excessive use by having too many people on the account. At the end of the month all IP addresses of people who haven't payed are removed by some cron job.

Here is my question. Does anyone know the Paypal API and how I could interface with it to allow the user to make a payment from my site and then trigger IP address addition to the database?

Need help, please.

Yes, your identification scheme won't work, IPs change and can easily be spoofed. MAC addresses too. You're talking about Identity/authentication -- that's what logins are for. I suggest you simply integrate with social networking sites (to lower friction for those who use them) to provide identity, and have your own login service for those who don't. Alternatively, you could put some kind of user-specific certificate that expires monthly behind a paywall (you'll still need to provide a way for a user to get it again if it gets lost, and if you want to automate that process you'll need a login system anyhow), and use it as a token necessary to access your site's content or access its services.

Another option would be to use the Patreon platform to manage subscriptions (which would allow you to do auto-pay too) -- its not known for being used as such, but it is effectively a platform for digital subscriptions. If the Patreon image is not suitable for your needs, it's based on Overdrive which you could integrate directly with your own site.

Nah, not interested in using IP addresses now. I can just stick to https and passwords. The paypal thing sounds cool. Yep, I want to create successful mobile games on phones and skip the whole google play thing. They charge too much for paid apps.. 30%, that's a lot!

Nahh...

Bah, humbug and a pile of bbq sauce. It's good. Just needed an example of how to do this.