Re: Unable to purchase coins (PC vers.)

I had this same issue but figured out what the problem was.  When I checked the Origin in game overlay by going to Origin (top left corner), selecting application settings, and then going to the Origin In Game tab, the "Enable Origin in game" was properly checked, but the overlay was still not active in the game (when I pressed Shift + F1 keys).  The proplem was this - go to My Games in Origin and then right click the Plants Versus Zombies Garden Warfare picture / icon - then select Game Properties.  A window pops up - make sure that the "Disable Origin In Game for this game" is not checked.  If it is checked, your overlay will not work no matter what you have selected in the other settings areas of Origin.  Once this box is unchecked, your overlay will work and the "Purchase Coins" option will be displayed in the Sticker Shop.  Hope this helps.