Please, last year in 2016 I used avast free of the version of 2015 I made time to another scans but I forgot to update it
My question is even though avast not updated dotés it detect and rhé threats viruses?
Thank you
Unless there has been a major tech change to the virus engine, older versions will detect new malware if it recive signatur updates
Well, update it now.
So it was still valid he was doing his normal job!??
If there had been a threat so it would have detected it right!!
Update Avast and run a full scan.
i have done it il was the last mouth this new update ,but i just wanna know if le last one would have detected the threats if there had been
Well, we could only guess and that wouldn’t help much. 
A scary but true fact is that there is no anti malware software that will detect (and/or block) the newest threats and there never will be.
It is like with humans, first there is the disease and only after it is known, doctors (scientists etc) can go look for a (possible) cure.
Only thing we can do is use our brains to reduce the chance to get ill as much as possible.