确认订阅设置已经正确配置，包括权限、商品ID、测试账号等。特别是需要保证订阅类型为自动续订。

确认代码中实现了自动续订功能。可参考如下示例：

public class BillingService extends Service implements ServiceConnection, 
PurchasesUpdatedListener {

    private BillingClient mBillingClient;

    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        mBillingClient = BillingClient.newBuilder(this)
                .setListener(this)
                .enablePendingPurchases()
                .build();
        mBillingClient.startConnection(this);
    }

    @Override
    public void onBillingSetupFinished(BillingResult billingResult) {
        if (billingResult.getResponseCode() == BillingClient.BillingResponseCode.OK) {
            List skuList = new ArrayList<>();
            skuList.add("monthly_subscription");

            SkuDetailsParams.Builder params = SkuDetailsParams.newBuilder();
            params.setSkusList(skuList).setType(BillingClient.SkuType.SUBS);

            mBillingClient.querySkuDetailsAsync(params.build(),
                    new SkuDetailsResponseListener() {
                        @Override
                        public void onSkuDetailsResponse(BillingResult billingResult,
                                                         List skuDetailsList) {
                            if (billingResult.getResponseCode() == BillingClient.BillingResponseCode.OK) {
                                for (SkuDetails skuDetails : skuDetailsList) {
                                    String skuDetailsId = skuDetails.getSku();

                                    if (skuDetailsId.equals("monthly_subscription")) {
                                        BillingFlowParams billingFlowParams = BillingFlowParams
                                                .newBuilder()
                                                .setSkuDetails(skuDetails)
                                                .build();
                                        mBillingClient.launchBillingFlow(activity, billingFlowParams);
                                    }
                                }
                            }
                        }
                    });
        }
    }

    @Override
    public void onPurchasesUpdated(BillingResult billingResult, @Nullable List purchases) {
        int responseCode = billingResult.getResponseCode();

        if (responseCode == BillingClient.BillingResponseCode.OK && purchases != null) {
            for (Purchase purchase :