I just purchased the paid version of Portal Keeper from snowcovered.com
On installation I'm getting the following error:
Failure File specified in the dnn could not be found in the zip file: Aricie.PortalKeeper.dnn.Merge.Xml
After looking at the Archive - this file is definitely missing. Please contact me asap, I also opened a ticket with Snowcovered. 
Hi, sorry for that, apparently there was a mistake with our last package. We'll make sure to release a new package on next Monday. In the mean time, the missing file is a temporary file and can be safely ignored. You can try to remove the corresponding line in the .dnn file and proceed again with installation. Cheers