How much memory and storage does a website take on a server?
You should be fine with 1GB server ram, and 256M set for PHP. Keep in mind you won't be running a huge site with it, so also invest in getting caching like memcache and something like varnish going as well. I'm not sure if memcache is PHP7 ready yet - but using php7 will gain some performance increase as well.

However if you're looking for free hosting, I think you could also try Acquia Cloud Free.