You added that listener code? As the name implies Codeless IAP doesn’t use scripting like that, you are mixing Codeless and Scripted IAP. I would suggest that you get the GrantCredits example in the documentation working first before adding any customization. This is the typical development flow, build on success rather than spending time debugging broken code. Please review the Sample IAP projects here, the first is Scripted, the second is Codeless Sample IAP Project and Unity - Manual: Codeless IAP