There is no help! Unless they make it compatible for use with the iOS4 it likely won't work. Why would you need this considering the iPhone 4 pretty much has its own memory management system built in?
Ahh, yes well that makes sense. They will have to make it compatible with the iOS4. You may want to go into iTunes and click on the Developers Web Site link and ask them if they are working on a new version.
I seem to recall Steve Jobs banning all the memory management apps a while ago because they weren't sandboxed. If iOS 4 killed your app, I don't think your going to get an update without jailbreaking (which you probably can't do because your on iOS 4).
Apple killed memory-freeing apps some time ago. Even with my iPhone 4, however, I've been using an old version of iStat that has this feature. As with any computer, after a while, the memory needs to be cleared. The best way to do this if you don't have a working app is a soft restart. (Maybe ~ once a day.)