Freqüency of ads

Hi,
I'm just about to finish a lvl-based game in which you have to complete a level in order to unlock the next one. I wanted to implement rewarded ads by giving the user an extra opportunity by watching an add. My question here is if there's a maximum amount of adds an user can watch everyday, so I can decide to allow only one extra opportunity every try or more. Searching the forums I've seen a post in which it is said that a user can only watch 25 adds per day, but that's from 2016. I'd like if the situations remains like that. Also, I'd like to know what happens if an user has already watched 25 adds and clicks the rewarded add button. It is something I have to manage myself or managed by unity ads?
Thank you and sorry for my english, I know it's not very accurate.