For licensing and installing Enroute, see: Activating your License and Downloading Enroute and Installing Enroute
When there is an update to Enroute available, you will be notified when you first open up a new or existing file. Click yes and close Enroute. Save any work if necessary.
A website with a Download link and your activation code will appear. Copy your activation code down and then click Download Now.
A .zip folder will download. Extract the contents somewhere convenient.
There are two items within the .zip folder. Open the folder with "64-bit" and run the .exe file inside. (If you know if you've installed the 32-bit version, open that folder instead. The vast majority installed the 64-bit.)
An installer will open. Click Next.
Point the destination to your existing Enroute folder. Normally it is C:\Enroute7, but you can click Browse... to find the proper folder.
The software will then update. Click next when finished, then Finish on the next screen. Enroute 7 is now updated to the latest build.