In case of Windows server on Tukaeru Cloud or Cloud VPS, user becomes responsible for keeping their system up to date.
Go to "Start" -> "Control Panel" -> "System and Security" -> "Windows Update"
(or in case of viewing control panel by icons just "Windows Update")
From left menu click "Change settings".
Confirm Windows Update settings.
If you choose the recommended "Install updates automatically", you will not need to worry anymore, as updates will be automatically done in the background. However, as some of them may require shutting down the system, server may restart itself unexpectedly from time to time.
If you think that it may be a problem for you, than please choose "Download updates but let me choose whether to install them". In this case, you will need to manually install updates, and maybe restart the server in the process, at your convenience.