Private equity firms are organized as entities that solicit investment funds from investors like pension funds, college endowments, etc. The role they play is to invest those funds by buying companies which they actively manage to increase their value, then a few years later they sell the companies or take them public through an IPO, creating a superior return on investment for the participants in their investment fund. The private equity firm, in this case Bain, takes fees for all the work they do in finding companies to buy as well as fees for their ongoing service in managing the companies while they own them. When the companies they buy are sold, Bain takes a "preferred return" (typically 20% of the capital gain), then the rest of the gains are distributed pro rata among the firms who invested in their closed end investment fund.

Almost always the individual investments, the "deal" where Bain would buy a company, are organized as partnerships within Bain and the investment fund itself. The key Bain people involved in finding the investment and subsequently managing it, along with the key managers of the company being purchased, are given allocations of the stock of the company. These allocations of ownership to those involved in managing the company is done to incent their work and skill in doing the things to create increased value for the investment companies. So when the company is sold, both Bain as an entity as well as their individual partners and the company managers profit from the sale of the company owned by Bain. In a lot of cases, allocations of the stock of the companies owned by Bain as well of a share of Bain's preferred return are given to Bain's owner and top managers, including Mitt Romney.

Any profits from the sale of the stock fom the investments isn't paid to the owners of the stock until it actually occurs, when the company is sold or taken public. So when Mitt Romney stepped down as CEO of Bain, he still would have retained partial ownership of the companies owned at the time of his leaving the firm, and also his partial ownership in the preferred return of the investment fund he was involved in raising while active in the company. Then in succeeding years, as those companies were sold, the value of his ownership shares would be paid to him, even though he had long since stepped away from active management of either Bain or the companies they invested in and owned. Such payments to Romney could be expected to continue for years after he left active management of Bain.

So could Romney be "paid" even though not employed and actively managing Bain? Absolutely. Could a critic or political opponent construe those facts differently for their own purposes? That's pretty obvious, isn't it?