Pay-per-install (PPI)
Advertiser pays publisher a commission for every install by a user of usually free applications bundled with adware applications. Users are prompted first if they really want to download and install this software. Pay per install is included in the definition for pay per action (like cost-per-acquisition), but its relationship to how adware is distributed made the use of this term versus pay per action more popular to distinguish it from other CPA offers that pay for software downloads. The term pay per install is being used beyond the download of adware.Some botnets are known to operate PPI scams to generate money for their operators. Essentially, the compromised computer with the bot agent is instructed to install the software package from a registered PPI source via the bot's command and control system. The bot operator then receives payment from the PPI agency and, after a short period of time, uninstalls the software package and installs a new one