/// <summary>
/// Saves receipt data along with the product id on the device.
/// Optionally supports encryption.
/// </summary>
public static void SaveReceipt(string id, string data)
{
string key = idPrefixKey + id;
if (instance.encrypt)
{
key = instance.Encrypt(key);
data = instance.Encrypt(data);
}
PlayerPrefs.SetString(key, data);
PlayerPrefs.Save();
}