Don't trust anyone who says they don't stick or don't last, they are clearly not following instructions. Mine lasted a month and a few days. They even included further instructions on how to make them last longer which I followed.
I love them so much!
I didn't realise on the UV light there is a tiny switch to keep the light on, so you don't have to keep hold of the button.
To remove them/the glue after they naturally fall off, use floss.