I like to recommend installing the free demo version ahead of buying and check the need for session management. The OC Session Manager module is largely intended for OpenCart 3. Opencart stores some consumer details (language, currency, cart, etc.) in PHP sessions. OpenCart can store this details in two approaches: https://jaredhhgbw.blogdun.com/32442546/the-definitive-guide-to-opencart-backup-and-restore