Preventing database/ layout changes

If I understood it right, for example, my customer must have the developer version, to upgrade to a newer servoy-project I have made.
But if the customer have the developer-version, he can make changes to the servoy project.

Is it possible to prevent this??

Servoy ships with full security preferences so you can configure how you wish but it is possible for a client to open different solutions if that is what you are after…

HTH

No I mean acces to the design-mode! Can I prevent this?? without losing the ability to upgrade?

Currently it is not possible, it is scheduled to be built very soon though.