Yeah it's enough, your disk cache is hardly used around 63 megabytes, and 208 megabytes is cached and that's why 43 megabytes is remaining in RAM. Linux caches the frequently uses processes in order to speed up the their works, yet 43 megabytes remaining means, it's fine for the time being, but I would consider to upgrade to 1GB droplet when the number of users hit 5000/day, so technically 10,000/day is enough for a 1GB droplet depending on what the droplet is used for. of course this may not pertain to all the people as, the droplet may be used for various purposes. If it's just static contents, then it can handle even millions of users without any problem. So these numbers are only for your current setup, but when you keep adding more contents, when you install new plugins/packages, when you get more visitors the server may need more power to handle all the data.