Hello,

For compatibily with an existing development, I need to use the 3.0 version.

Is it possible to download and use this 3.0 version if I buy the current 3.1 one ?

Thanks

Yes. Though it's recommended you upgrade to v3.1. There are very few, if any, breaking changes, so it's not a lot of work to migrate to v3.1 from a 3.0 codebase. The 3.1 breaking changes are documented in the llblgen pro documentation for the o/r mapper framework you're using.