Hi Nicolas, as a content creator myself, I completely understand that you need to pay your bills. And you absolutely have every right to charge for the hard work you've put into making this wonderful extension.
However, I feel this is somewhat of a problem as we have no way to disable the order being created without payment. Customers could very well get through the checkout and then realise there's an issue with their card and close the site, only to log back in, find their un-paid order in their account and have no way to pay for it.
We as the site owners are going to end up with customers contacting us asking us to remove un-completed orders, or asking us where do they go to pay for it? With nothing for us to do, unless we upgrade to a paid version of HikaShop.