A semi-untethered jailbreak has some advantages such as disabling the jailbreak to remove faulty tweaks. While this is good, the most annoying part is that the Yalu jailbreak app expires every 7 days, which means that you have to use your computer to reinstall it every time it expires.
If the Yalu app expires and the jailbreak is disabled, then there's no way that you can re-jailbreak unless you re-sign the app using your computer. This is why a new jailbreak app was developed to let you know when the jailbreak app expires.
Known as CertRemainTime, this tweak shows the amount of time remaining before the jailbreak app expires on your iPhone. The tweak displays the exact number of days and hours remaining, as well as the date of expiration and installation.
This tweak comes in handy to those who use a free Apple ID to install the Yalu jailbreak app, because it is valid for only 7 days before expiring.
Keeping the jailbreak app signed at all times can get annoying as you won't always have a computer nearby to re-sign the app as soon as it expires. Luckily, there is a jailbreak tweak called Extender Installer that automatically re-signs the Yalu app and other sideloaded apps as soon as they expire.