Include a portable app so that you can use it on all your systems without having to install it to all of them

Normally this would be an acceptable idea for free or open source software - but when the software is licensed to run on a single computer - putting the software on a USB stick so it can be run on any computer in the world, doesn't really work out in favor of the developer.

But users who want to purchase one license and use the software on every computer they own think it is a great idea.

If you need a portable version you can run anywhere - get CCleaner.