Use premium accounts only for content you have rights to download. Respect hoster terms of service.
Ironically, the only working model that resembles the promise of a premium database is not a database at all, but a (Real-Debrid, AllDebrid, Premiumize). These are legitimate paid aggregators—they buy one enterprise-level account with each hoster and legally share it among their subscribers via API. jdownloader 2 premium database exclusive