The undeniable potential benefits of learning analytics (LA) in education have led to growing investment in developing and integrating LA systems into K-12 schools. Yet, the actual integration and adoption depend on levels of teachers' acceptance and usage. This study aims to propose a conceptual model to reveal the decisive factors affecting teachers' adoption of the LA system for evaluating teachers' sustainable LA usage through the integration of Information System Success and the Technology Acceptance Model. The variables used were system performance quality (SP), information quality (IQ), perceived usefulness (PU), and intention to use (IU) via the partial least square structural equation modeling (PLS-SEM). Furthermore, the moderation effect of teachers' AI literacy level (LIT) between dependent variables (SP and IQ) and PU was analyzed. The results indicated SP (sub-constructed by accessibility and human awareness) and IQ (comprised of reliability and relevancy) have statistically positive influences on PU and IU, where LIT played a moderating role between IQ and PU. This study contributes to our understanding of teachers' perceptions regarding LA system integration through a theoretically grounded analysis of empirical data from the K-12 school education context and highlights important areas of development for better LA integration into teachers' practice.