Hi Uwe
I'm not sure, but I guess no.
This is a one time license fee that allows you to continue using the downloaded Bacula Windows binaries for as long as you respect the terms of the license.
After the 3 month download period, if you want an updated Bacula Windows version, you will need to purchase a new license.
But sometime ago Kern has said that plans to release current version of bacula windows clients without any costs for community.
Maybe in the end of this year
Best Regards
Wanderlei