We have 3-tier applications, one is for services. We do not see a good development practise in having data access libraries on the customer side - and now with VG it is compulsary - Is it possible to solve this procedure in another way?

With the current version, you can secure Web Services without deploying data access libraries on the client,
because VG libraries and data access libraries will be installed on your server with you Web Services.

The data access library may be needed on the client when you want to secure a thick client
(winform app for instance) with VG, because VG libraries have to communicate with VG repository.
If you do not want to install data access libraries on the client, you need VG Server - included in VG Enterprise Edition.
The VG libraries deployed with your winform application will communicate with VG server, VG server itself will communicate with VG repository.