Is there a way to make my decks private? I want it to be accessible only to those emails that I allow (will be based on their AnkiWeb account). And I want it to be accessible only in a limited amount of time (like a year). Please please make it possible :<<
AnkiWeb doesn’t support that, and Anki’s open nature makes this hard/impossible to implement.
AnkiHub allows you to distribute decks to certain users only, but it doesn’t provide protection from unauthorized sharing, and it requires users to have AnkiHub subscriptions.
also, this option exists: Contributing - Anki Manual
Generally people who want to sell decks for a fee simply distribute them as is. Most individual sellers operate on a small scale, so they lack the notoriety to worry about unauthorized redistribution and no opportunity loss occurs, increasing their basic sales volume is a more important challenge for them.
Also it is not common practice to set limits on the learning period, typical learners request backups of their learning data so it is standard to allow free export of cards, only malicious commercial apps deliberately remove this feature.
For sellers of large scale decks there is an advantage to implementing measures against unauthorized distribution (e.g. Authors of books and textbooks, or prominent influencers). In such cases they create and distribute simple apps or websites, because they only want to sell their decks and do not need advanced tools, so they do not use Anki, and do not share code because it is for commercial purposes.
Since Anki is an open source project, it is developed by many volunteers and both developers and users prefer free tools and resources, so tools for paid developers are rarely developed in Anki and are unavailable and in most cases such tools or apps become targets of boycotts (such tools and features are also highly likely to become competitors to Anki).
Anki license permits commercial use of its code so technically these are legally possible (be careful with trademarks) but those tools and ways are not in the community and are not likely to be shared, so if you want to do that, you’ll need to look elsewhere or create everything yourself.