We want to provide to hotel guests in a number of hotels ISP services.

The guest wants to go onto the Internet NOW.

Which Paypal suites this type of transaction -- giving us irrevocable
confirmation of payment.

We can't afford to provide the service and then find out days later
that the authorization was revoked.

Paypal offers these eight services according to
https://www.paypal.com/IntegrationCenter/ic_home.html

Express Checkout
Website Payments Standard
Website Payments Pro (US)
Website Payments Pro (UK)
PayPal Mobile Checkout
Payflow Link
Payflow Pro
Website Payments Pro Payflow Edition

Thank you.