You don't need GLTools to change resolution. Use Android Debug Bridge (ADB): adb shell wm size 1080x1920 This does exactly what GLTools does but system-wide.
The Premium Key provides access to a wider range of customization options: gltools premium key top
It looks like you're asking for a for GLTools (a popular graphics optimization/tool app for Android, often used with GameLoop or rooted devices). You don't need GLTools to change resolution
If your phone struggles with heat or lag, the Premium version lets you change the resolution of specific apps. Dropping a 1080p game to 720p can provide a massive performance uplift while keeping the device cool during long sessions. 3. FPS Counter and On-Screen Display If your phone struggles with heat or lag,
This is often a separate "key" app or an in-app purchase that unlocks the advanced features.
Most modern versions require a "Plugin" (the Premium Key) to be installed as a separate small app.