Is it worth buying premium dog food for my dog?

It's not exactly black and white like that - it really depends on your dog's health and what he's eating right now. If your dog has some digestive issues, allergies, or your vet recommends it, then yeah it's worth investing; but if he's doing fine on regular food and he's healthy, the actual difference is smaller than people think.

My dog started on premium food after he had some skin issues and it made a huge difference, but that was because the vet specifically recommended it. If yours is healthy and eating well, you don't need to spend extra - regular food does the job.