Have seem some topics have this notification at the bottom of replys, what is this used for?
And, is that a function can be enabled on self installed instances?
4 Mi Piace
Hey,
Its used mostly in topics where you have docs and you want to keep the topic free from old replies / clutter etc. After a set period of time you can automatically delete the replies. If a post has 5 or more likes it does not get deleted. This value can be changed by this setting skip auto delete reply likes
This feature can be used on self installed instance
12 Mi Piace
At the more frivolous end, it can be used for game topics too. We have some A-Z, Last Letter, etc chain-style games, and having a topic timer allows those to be cleared out automatically so they don’t bloat out. 
We’ve even used it as part of the game structure for a couple, where the timer is set for 1 day and the idea is to keep the ‘chain streak’ going for as long as possible before being wiped out back to the OP/stub post.
Probably not useful to more serious forums, but thought I’d throw it in for good measure. 
6 Mi Piace
Can this be enabled in a way that selected replies are kept?
The use case would be to build up a FAQ-like list of useful comments bellow while removing clutter, keeping the question and the answer or something like that.
3 Mi Piace
The ones with 5+ Likes are kept, as @ondrej explains above. However, you can copy and paste any useful information from the comments/replies and add it to the OP if that’s a better place for it.
5 Mi Piace
Trovo solo l’impostazione per salta l'eliminazione automatica dei like alle risposte
Dove posso attivare e modificare il numero di giorni per l’eliminazione automatica delle risposte su un argomento? O, ancora meglio, può essere impostato per categoria?
1 Mi Piace
Non importa. L’ho trovato nelle impostazioni del Timer argomento su ciascun argomento.
3 Mi Piace