Guys, I put the liquid on, spread it with a small sponge, they looked perfect, but the thing is that it's been a week and it still hasn't dried. I go every day and touch it and it's still like it's been coated with something like thick oil. What's going on, does anyone know?
A simpler headlight kit had turned into crystal the next day.

Polishing headlights with water sandpaper, starting from 800 and reaching up to 2-3 thousand depending on the desired result that each person wants. Then apply a polish and after that the Sonax coating. It does what it promises, leaving a hydrophobic surface and keeping the headlight clean. I haven't tried them in the summer yet to see, but I imagine that what the others say in the comments is true. One bag is enough to properly apply it to the front headlights twice.

I polished the headlights and applied varnish for maintenance, even though it's not ceramic, it does a good job. Although it claims to provide protection for one year, I recommend applying it twice, especially before summer. The individual packets are sold separately in many stores for around 2.5 euros. One packet is enough for two passes on the front and back of the car's headlights. After three years of doing this, they still look brand new.