I have a Ghost newsletter that has a premium subscription set up with Stripe.

Basically, people go to the /subscribe page, choose a price, get redirected to Stripe, and then upon success, get redirected to the main page /, where the url will now have this appended:

?stripe_portal=success

I want to track Google Adwords conversions when the purchase is made.

I don't know how to do that, as conversion code on the main page would also count normal visits.