model:
class Subscription(models.Model):
    user = models.ForeignKey(User)
    stripe_id = models.CharField(max_length=255)
    subscribed = models.BooleanField(default=False)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)
    expires = models.DateTimeField(null=True, blank=True)

    def save(self, *args, **kwargs):
        self.expires = datetime.datetime.now() + datetime.timedelta(365)
        super(Subscription, self).save(*args, **kwargs)


view:
@require_login
def payment(request):
    context = {}
    if request.method == 'POST':
        token = request.POST['stripeToken']
        customer = stripe.Customer.create(
            description = request.POST['email'],
            card = token,
            plan = 'premium_annual',
            email = request.POST['email'],
        )
        subscription = Subscription(
            user=request.user,
            stripe_id=customer.id,
            subscribed=True,
        )
        try:
            if Subscription.objects.filter(user=request.user).exists():
                context['subscription'] = subscription
            else:
                subscription.save()
                #UserProfile.objects.get(user=request.user, is_premium=True).save()
        except IntegrityError:
            messages.error(request, "Subscription already exists.")

        context['publishable'] = settings.STRIPE_PUBLISH

        return HttpResponseRedirect("/activities/all/")

    form = StripePaymentForm()
    if Subscription.objects.filter(user=request.user).exists():
        messages.error(request, "Subscription already exists.")
        return HttpResponseRedirect("/activities/all/")

    context['form'] = form
    context['no_left_bar'] = True
    return render_to_response('signup/premium_payment.html', context, context_instance=RequestContext(request))