Article processing charge is necessary to cover operational expenses. As an Open Access publisher, APALM does not generate revenue through subscriptions, as the journal is freely available online. Instead, a modest fee is paid by the author, institution, or funding agency to support the essential final stage of publication. This fee covers all aspects of the publication process, including peer review, editing, publishing, online hosting, and archiving, ensuring immediate access to the full-text article. The APC is only applicable if the article is accepted for publication.