Please follow the steps below in order to remove the license and revert Veeam Monitor v5 to the free version, if necessary:
1. Remove the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Veeam\Veeam Monitor for VMware\license
2. Restart the "Veeam Data Collector Service" service.
3. Make sure that FreeLicense is enabled in the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Veeam\Veeam Monitor for VMware\license
As the result, the free license will be enabled instead of the previously assigned license: