In-app purchase plugin

Hi everyone, i'm looking a plugin to use in-app purchase in game, but i got confused between Ultimate Mobile, Open IAB and Soomla.
First, i choosed the sample of Open IAB from here: https://github.com/GrimReio/OpenIAB-sample-game
it tested ok with product ID of my game in Google Play, but when i replaced with fake ID from GP like android.test.purchased, android.test.refunded, it couldn't show sample title with fake VISA to test.
After that, i deleted the plugin in the above sample and replaced by Ultimate Mobile. It could show both my ID or fake ID, but i noticed the text still showed "Product purchase failed", even when i choosed sample title of fake ID, it showed "Payment successfull" (i created another empty project and just used example of UM, but the purchase text still failed).
And the point of UM is i didn't know how to use purchased product in that sample game (https://github.com/GrimReio/OpenIAB-sample-game). I bought succeedfull a product, but it didn't show or change on the game (in the sample, i have repair tool to buy, and its number will increase when buy succeedfull).
In Soomla plugin, i got the same problems like UM, so if anyone know how to fix, please help me. Thank you