There are only a couple of things that can help improve memory issues.

Work with fewer images
If you have multiple images opened at the same time, you will use more system resources, including memory. It is recommended that you close out images that you are not actively working with at that time.

Close out other programs
If you have other programs running at the same time, they can tie up memory that PhotoImpact Pro could use. It is recommended that you close out all programs that are running at the same time. You may also want to look at disabling startup items. These are programs that run every time that you restart your computer. Directions on how to disable those can be found here.

Install more memory
If you install more memory, your computer should perform better. This performance improvement will apply to all the programs that run on your computer. To install more memory, you may wish to consult with the computer manufacturer. They should be able to provide information on what type of memory needs to be installed.