OneBox does not officially sell or support older versions of its products.
If you are still using OneBox MVP, you can purchase licenses (activation keys) through partner distributors.
If you are using older versions of OneBox (CRM+ERP, Revolution, Next, White, ...), you will first be upgraded to OneBox MVP, and then you will be able to purchase activation keys through partners.
You can view the version history here https://1b.app/en/version/.