How to close IAP or how to Quit App properly Android

Hi, Im building a small game, it is finished, so i implemented IAP to get some money from it.

Everything works fine, but after IAP implementation small bug appeard. When you quit the game by

  Application.Quit();

And then relaunch the app, it shows white screen for like 3 - 4 seconds, and then the app relaunches.

The problem is in the IAP, it doesnt close it on the Quit and it closes it during the relaunch phase.....

So i would like to know, how can I close IAP before i quit the program, or how can I send player to their home screen without quiting the application.

Thank for any advice and Im sorry for my english :))