This study empirically analyzes the growth trajectory and transaction patterns of the stablecoin-based payment ecosystem by examining RedotPay, a blockchain-based digital asset payment service, through on-chain data. Transaction data of USDT and USDC conducted on the Ethereum, Tron, and Solana networks over a 22-month period (December 2023 to September 2025) were collected and aggregated on a weekly basis. The results show that user deposit inflows to RedotPay increased rapidly from an average of $2.1 million during the initial 10 weeks to $52.5 million during the final 10 weeks, while the estimated settlement outflows rose from $0.41 million to $32.9 million over the same period. By network, Tron-based USDT accounted for 70-80% of total inflows, Ethereum for 15-20%, and Solana for 5–10%, indicating Tron’s dominant position in RedotPay’s ecosystem. The average deposit size steadily declined, while the share of small deposits below 1,000 USDT increased from 31% to 70%, suggesting a rapid expansion of small-value users. Leveraging the transparency of blockchain data, this study microscopically identifies the actual usage patterns within the digital asset payment ecosystem, empirically demonstrating that stablecoin payments are evolving from an early-adopter phase toward a mass-market payment medium. The findings provide valuable implications for digital asset payment service providers in strategic planning and for regulatory authorities in designing balanced policy frameworks.