irishguy28

If you're absolutely certain that no payment was taken - and here you should also check that you didn't accidentally use some credit/debit card other than the one you think you used (or did somebody else pay? Client/employer/partner/friend/parent/somebody else?) - then of course KLM can cancel the ticket. If you really didn't pay - and if nobody else paid on your behalf - then you don't really have any right to the ticket.

Also - did you book directly with KLM? Or did you book via some third party agency? In the past (not since the pandemic), I frequently bought KLM tickets from third parties, who frequently offer tickets at a discount - and the transaction would appear as them paying KLM with their own payment method, while separately charging me a lesser amount on my credit card. It seems highly unlikely, however, that any third party agent would pay for your ticket and forget to actually charge you, just as it seems unlikely that KLM would issue the ticket without remembering to take payment from your card if you dealt directly with KLM.

I don't think any of us can help you any further with this. But if you are certain you didn't pay, then I would warn you that the ticket could be cancelled at any time, with no prior notice - even after you may have checked in or begun travel!!!!