Once the 30 days is up you will not be able to use WindowBlinds.
Correct.
When the trial expires Windowblinds 'stops' working. Meaning whatever skins you have will also not work. Leaving it installed is like having an app that does nothing. No app ... no skins. The skins will not work without it. Does that answer your question? I had the trial version also and found this out the hard way.
Not correct.
The skins you've downloaded remain in a library its just the trial version will no longer display them. When you purchase the full version you will have all your skins so long as you don't delete them.
Correct. CarGuy1 is also correct.
You can move and save these skins (rename the file holding them to "skins.bak) and then uninstall the trial Windowblinds through Impulse. Reboot. Then you can run CCleaner to scrub any leftover registry stuff.
I would suggest that after doing that, buy an Object Desktop SUbscription and reinstall the apps through Impulse and move the skins from inside the .bak file to the themes folder in Windowblinds, then open the Windowblinds config window and choose the option to rebuild the list of your skins.
OK?