Re : How to map software versions to licenses? How to enable older Software to run with a newer license?

What I tried to ask is: Let's assume that our license terms state (in fact, they do) that the latest license (v3.0) includes the rights to run an older software version by using that latest license (Feature ID 1003).

The user in my scenario still has v2.0 installed, but let's assume they purchased and activated v3.0. Consequently, when starting the software version v2.0, they should have the rights to use it, because the v3.0 license includes the rights to use v2.0.

You may ask why this is important: In our experience, many users don't like to be forced into an update. They may be used to be working with v2.0 and for some urgent work to be done, they can only be fast with the software they know by heart. An update may slow them down for their project. On the other hand, for our sales team it's best practice to write offers for the current software versions only (we have to avoid selling licenses for older versions, it makes pricing too complicated). That situation leads to the requirement, that older versions should run with latest licenses.

I understand your concern that you also include feature (in latest license) required for previous application version per your customer's requirement. That approach is helpful if you use different license terms for different application versions. Otherwise, you may use only one feature for all your application versions and only license update (with extension) needs to be provided when required. 

I'm aware that it would be possible to artificially create a downward compatibility like this, if older versions would also access the feature ID's of upcoming versions. Let's say v2.0 would be so smart to access 1002, if this doesn't work, it tries to access 1003, then 1004, then 1005. That would be a way to do it, but it seems more like a workaround or a hack than like professional version management.

This wont be a recommended approach per my understanding. As suggested, please feel free to get in touch over email if needed for better approach and solution.