Trouble with scratch cards and subsequent purchases

[natrat22]

I think I msut be misunderstanding sometingor misusing somerthing as I'm having ongoingi ssues setting up free access correctly.

At a resort i manage with Firstspot guests get 500MB of download quota free, if they want to use the internet after that they need to buy a plan.

I generate scratch cards using the free access plan to do this. That all works fine, they login with a simple 8 digit number and its great.

However, when that expires, I had assumed that the scratch card number just couldn't be used at all anymore, but it seems they are being prompted to purchase a plan from the cart upon logging in again with the scratch card ID. Is that by design? I had assumed they just couldn't do anything and they would then have to create their own username and password from the login page and purchase a plan.

but does the scratch card effectively work just like a username and password in one? Can they purchase from the cart on the scratch card login after the initial free access plan expires?