Updating a record when landing on a page

I'm used to the normal way of updating a record when a form is submitted, but have a requirement to update a record simply by landing on a page.

The context is basically updating a 'paid' field to yes if a payment on PayPal has been successful.

So the idea is that people click to make a payment for a property, which is listed in a table of properties, and includes a field 'paid'. They go to the Paypal site, and if the payment is successful they are returned to a 'success' page.

And the action of arriving on that success page is enough to update 'paid' to 'yes'.

Is there any way something like this could easily be achieved?

I'm not sure it would be and that it would need some sort of workaround eg a simple form with a button to continue, which would update the field.

Which would work, but only if people actually did click on the button.

Hope that makes sense, thanks.