When a subscription is created, the response includes an approval URL, like this:
https://www.sandbox.paypal.com/webapps/billing/subscriptions?ba_token=BA-242856SD393XYZ789
Unfortunately, the documentation does not seem to define the lifetime of the approval URL. Does it have a lifetime, or does it never expire?
In previous versions of the API, approval URLs seem to have had a lifetime of 3 hours. In Sandbox, this does not seem to be the case with the current API. It could, of course, be different in Production.
