The group - Mel, Mel B, Geri Halliwell, Victoria Beckham and Emma Bunton - reformed for a string of shows in 2007 and 2008 and despite speculation they will reunite again for next year's London Olympics, the singer can't see them going out on the road any more, even though they are now closer than ever.
"We've got such a Bond because of what we went through, so to be back in each others' lives is lovely.
"I don't think we'll tour together again, but then I never thought it would happen the first time so who knows?"
Mel, 37, also admitted she might pen her life Story One day - but only when she no longer cares about upsetting anyone with her memoirs.
She told Britain's Hello! magazine: "When you're older and at a pointing life where you don't care who you offend or upset, I think that's the only way to do it. Who might I offend? Ask me again in 20 years."