Instant apps can be used on your phone without installing them. It's like a portable program for a computer, go demo version. If you like the app, you can download or buy the full version on the Play Store.
Why do we need such programs? For example, to get acquainted with the application before purchasing the full version. Or to save space on the phone, so as not to install an unnecessary program, which you then immediately delete.
To use Instant Apps, you need to activate Instant Launch on your phone. Go to Settings> Google> Instant Launch. Choose the Google account with which you will work. Done.
Flip the switch to the On position. And on the same page you will see a list of all applications with this option.
If the program is already installed on the phone, then its full version will start, and not the “demo version”, as is the case with applications with instant launch.