When you're experiencing any sort of trouble with your server, it can be easy to assume that memory (lack of available RAM) is the issue and you may begin to worry as to whether or not you may need to spend money on an upgrade. However, you may not need an upgrade at all, especially if there are no server troubles to begin with.
Here are a few things to check first:
On your "Overview" page in Prisma, monitor the "Memory" usage bar. What percentage is at when your server is at peak hours? Be sure to check when players are online, not when it's just starting up or when the server is empty.
Go to the console. Do you see any notable errors? If the server is running out of memory, it may be telling you just that with an "Out of Memory" error.
Has your server been crashing? Check your file manager for crash reports and take a look. You could also have a report there that tells you whether or not the server is out of memory.
If you do find an "Out of Memory" error, you likely need to upgrade your server. If you're not sure what to upgrade to, please feel free to reach out to our team for help.
If you feel your server should not be running out of memory, it's possible there may be something else going on. Memory leaks may occur as a result of experimental and/or questionable plugins or mods that you've installed from various sources. You may consider disabling these until a resolution is found.
If you're running vanilla, you might consider changing your server type to Spigot or Paper. Either of these server types offer optimization where vanilla Minecraft does not, which can lead to enhanced performance and lesser impact on memory usage. Paper offers more customization in regards to settings so we always encourage its use in place of vanilla/Spigot/CraftBukkit/etc.
If you're running a modpack, you might consider disabling/removing mods you may not want/need in order to lessen the amount of memory the server needs. Alternatively, you may also consider looking to see if the pack as a "Lite" alternative or if there's another, smaller modpack that you may also enjoy.
If you don't find an "Out of Memory" error but you're still having server issues, we encourage you to reach out to our team and include any helpful details you may have. This means tell us what you and other players have been experiencing in-game (FPS lag, rubber-banding, block lag, etc.), how often you're experiencing it, whether or not you ever see error(s), server crashes, etc. Please refrain from including mass walls of text from your server's console/files as our team has access to this already. If you feel you need to share text from your server, please do so via a free text-sharing service, such as GitHubGist.