when she was a kitten, old enough to get the treatment. She wasn't able to reach around to lick it. The drop was placed high enough to prevent that. It was at the base of her head, right where it attaches to the neck. Physically impossible to reach with her tongue.
It worked well. She is an indoor cat in a city apartment with very little lawn. There are a few flowers and shrubs, but not located where I would walk close enough to pick up fleas or larvae.
The only time that she gets fleas is after a vet visit, possibly transferred from the vet after handing other animals. So she gets a flea drop treatment when she gets a shot. She's been very healthy and, aside from a urinary infection and later, an eye infection 5 years ago, she only goes to the vet for shots when they are due.
Try applying the "goo" a little higher up so your cat can't reach it. If you can catch the cat. Might be a 2 person job.
For pills, I ALWAYS crush them up in a teaspoon of canned food. No more than a teaspoon to be sure that she gets all of it, thoroughly blended with her favorite Fancy Feast flavor of tuna and shrimp. But the only time she gets a pill is before a scheduled vet visit. It's an anti anxiety pill to make her more manageable since she hates going there. I would not risk the shredding of my skin by trying to manually give her a pill.