I don’t know that the three month window is true. I’m still in that window for The Life Engineered and while heavy promotional efforts have died down after launch I don’t think that, as long as the book is on their platform, Inkshares will ever really stop pushing the book. Keep in mind that they don’t need to sell that many copies of a book before they gather the financial benefits of a paid service the likes of which you describe.
Also, this opens the door to writers complaining about paying for a service but being dissatisfied when it doesn’t meet their expectations. I see this coming from writers who may not have a full understanding of how important their own involvement in promotion is, even after publication.
Bottom line: As long as the book is on Inkshares, they have a vested interest in that book selling copies, so I imagine that promotion will be a continuous effort regardless.
