The Veeam Backup Free v9 is quite good but it lacks of scheduling the backup task. Fortunately, it supports powershell so you can leverage this following script to backup vms without upgrading to the Pro version:
1. Download and Install Veeam Backup & Replication Free v9 in a Windows machine (It's Windows Server 2008 R2 in my case):
Note that It may require you to install Microsoft .NET framework 4.5.2 and Microsoft SQL Server 2012 Express if your server does not have them.
2. Install PowerShell v3, it's Windows Management Framework 3.0 (the script works best with PowerShell v3):
for Windows Server 2008 R2, I installed the Windows6.1-KB2506143-x64.msu package.
3. Download this file and edit it with your own information (server name, email settings...)
4. Create a schedule task to run the script every weekend at 1AM for example. Everytime the backup finishes, It will send a report email to you.
Because you're using the free version of VEEAM, you can't backup vms simultaneously. The backups will be created one by one and may take quite a bit of time (depends on how many vms you have and how big they are). So plan the schedule carefully.