Here are the links to the Windows Service (for IIS 7.5 or lower):

msi Setup Package
Source Code

 Setting Up Instructions:

1. Install the .msi package on your windows server.
2. Open your "Services" and find the service named "DNNKeepAlive_Pinger" and Start the service.
3. You will get an error stating that the service Started and then Stopped. This is ok and it's expected to happen the first time you run the service. That's because the service automatically creates a folder called "DNNKeepAlive_Config" on your "C:\" drive and it also creates a "config.txt" file (inside that folder) when you run it the first time.
4. Open the "config.txt" file and change the url default entry ("http://www.YourWebsiteUrlHere.com") with your website's url.
5. If needed, change the minutesinterval entry to what ever minutes you want (the service will ping your website every X minutes you specify).
6. Save the changes you made to the "config.txt" and close the file.
7. Start the "DNNKeepAlive_Pinger" service again and everything should now work as expected.