This systematic literature review synthesizes evidence on how digital payments and social-commerce environments are associated with consumptive behavior among Generation Z and other young consumers, and it derives implications for digital micro, small, and medium enterprises (MSMEs). Three relevance-ranked searches were conducted through Sider Scholar using OpenAlex and Google Scholar discovery for peer-reviewed publications issued from 2020 to 2025. The searches yielded 140 hits. After deduplication, title and abstract screening, full-text assessment, and quality appraisal, 21 studies were included. Eligible studies examined e-wallets, mobile payments, buy now pay later (BNPL), live shopping, social commerce, fear of missing out (FoMO), impulse buying, compulsive buying, or financial self-regulation in Generation Z or young-adult populations. Screening and coding were completed by one reviewer in two documented passes; therefore, inter-rater reliability was not calculated. Thematic synthesis identified four recurring mechanisms: reduced payment salience and transaction friction; psychological distance created by deferred payment; persuasive social-commerce cues such as scarcity, immersion, personalization, and influencer presence; and individual moderators including FoMO, materialism, financial literacy, and self-control. The evidence does not support a universal causal claim that every cashless instrument increases impulsive purchasing. Rather, the association varies by payment type, product category, platform design, enjoyment, and user characteristics. Quantitative figures reported in this review are secondary results taken from the included studies and are not original estimates. The review proposes responsible digital commerce for MSMEs, emphasizing transparent total costs, non-manipulative interface design, proportionate use of personalization, optional cooling-off features, and financial-literacy messaging. These practices can support digital market growth while reducing avoidable consumer vulnerability.