Whether Lady's pregnancy was planned or a surprise, she should have seen the vet to make sure everything was going smoothly. If so, she likely had an X-ray, so you know how many pups to expect. If not, a vet visit is in order if you want to be sure she's finished delivery.
All in a Day's Work
By day 45 of Lady's pregnancy, an X-ray at the vet will tell you how many puppies she's carrying and if they're all alive. Knowing what to expect is a big help at delivery time -- all you have to do is count. If you're concerned because it's taking more time than you anticipated, consider the process can take as little as two hours or as long as 20 hours. Generally, a dog will deliver one pup about every 45 to 60 minutes, including 10 to 30 minutes of hard straining. It's not unusual for a dog to take a rest before she's finished; up to four hours may pass before she strains to deliver another puppy.
Time for the Vet's Help
If you didn't get a puppy count before Lady's delivery date, there's no way to know for sure if she's finished labor unless she's checked by the vet. If you're lucky or know what to look and feel for, you may be able to figure out if there's still a puppy in there, but without an X-ray you'll be working off a guess. You should definitely see a vet if she strains hard for longer than an hour or takes more than a four-hour break without producing a puppy.