試用期的貝寶定期付款

Question

我正在嘗試使用以下功能實現PayPal訂閱系統：

• 該應用程序的第一個月服務將完全免費，之后用戶將按月支付費用。

我已經編寫了以下代碼，如下所示：

BillingPeriodType periodType = BillingPeriodType.MONTH;
                    switch (subs)
                    {
                        case("Month"):
                            periodType = BillingPeriodType.MONTH;
                            break;
                        case("Year"):
                            periodType = BillingPeriodType.YEAR;
                            break;
                    }
                    BasicAmountType paymentAmount = new BasicAmountType((CurrencyCodeType)EnumUtils.GetValue("USD", typeof(CurrencyCodeType)), subType.Price);
                    BillingPeriodType period = periodType;
                    BillingPeriodDetailsType paymentPeriod = new BillingPeriodDetailsType(period, 1, paymentAmount);
                    ScheduleDetailsType scheduleDetails = new ScheduleDetailsType();

                    /*Free trial period of 1 month for monthly sub*/
                    if (periodType == BillingPeriodType.MONTH)
                    {
                        scheduleDetails.TrialPeriod = new BillingPeriodDetailsType(BillingPeriodType.MONTH,1, new BasicAmountType((CurrencyCodeType)EnumUtils.GetValue("USD", typeof(CurrencyCodeType)), "0.01"));
                        scheduleDetails.TrialPeriod.TotalBillingCycles = 1;
                    }
                    else if (periodType == BillingPeriodType.YEAR)
                    {
                        scheduleDetails.TrialPeriod = new BillingPeriodDetailsType(BillingPeriodType.YEAR, 1, new BasicAmountType((CurrencyCodeType)EnumUtils.GetValue("USD", typeof(CurrencyCodeType)), "0.01"));

                    }

                    scheduleDetails.Description = "//Some description"
                    scheduleDetails.PaymentPeriod = paymentPeriod;
                    createRPProfileRequest.CreateRecurringPaymentsProfileRequestDetails.ScheduleDetails = scheduleDetails;
                    CreateRecurringPaymentsProfileReq createRPProfileReq = new CreateRecurringPaymentsProfileReq();
                    createRPProfileReq.CreateRecurringPaymentsProfileRequest = createRPProfileRequest;

這給我帶來了巨大的安全隱患。

So let's suppose user subscribes for monthly subscription and get 1 month for free... 

This way, nothing stops the user to cancel the subscription the last day and then to re-subscribe once again and re-use the 1 month trial period for free...

目前在PayPal上的用戶信息中，我僅將ProfileID信息存儲到數據庫中。

有什么有效的方法來查看用戶是否在我的網站上使用了免費試用期？

Also another security concern to me is that user can simply re-register with new account and subscribe once again under completely different ProfileID

你們將如何解決呢？

Answer 1

我只是希望我不要誤會你的問題：

為什么不將用戶的PayPal電子郵件地址鏈接到注冊帳戶？ 在這種情況下，用戶必須使用其他Paypal帳戶，因此避免這種情況變得容易得多。

並且在用戶注冊時，用戶應該已經提供了他的賬單信息。 包括他的PayPal電子郵件地址。