Speaking to Journalism.co.uk Leonard said almost a year on from the launch of the trial, which could have been rolled out to other regions if successful, the title is now reviewing the model "with the most likely outcome of removing it".
The metered model was set up to allow readers to access 20 articles before payment was required.
"We set our threshold very high so as not to in any way limit our opportunity on the advertising, that was a good decision as the advertising has flourished for us in North America, so that we'd like to continue," he added.
But he said "the real challenge" has been that audiences outside the UK "don't necessarily stick".
"They don't necessarily have a meaningful reason to come back unless they really like [Middle East correspondent] Robert Fisk or the fact that we do [comment site] Independent Voices etc.
"So we're creating new reasons to engage with us and if we were the New York Times, and had a real following, particularly a subscription-based audience, I think we might have a different view on that.
"It's been an interesting experiment, we think that we've learned some things from it but from a commercial perspective it hasn't had the results that we did expect."
The Independent's iPad app, on the other hand, which was also announced in October last year alongside the metered paywall, is "meeting its objectives commercially", Leonard said.
"We have had some brilliant take-up from the advertising side".
He added: "We do bundle it now, and it's early days as far as bundling it with the print product, but that's been a very good marketing extension of our relationship with subscribers to the Independent.
"By having the opportunity to also look at the i and the Evening Standard we'll probably be reviewing that formally over the coming months, as others are doing, a bit of consumer research etc, to gauge real satisfaction."