Modal Popup 2 times per session

I use this to show modal popup:

    let customModel = document.querySelector(".custom-model-main");

    let closeBtn = document.querySelector(".close-btn");
    closeBtn.addEventListener("click", function() {
        customModel.classList.remove("model-open");
    });

    document.addEventListener("DOMContentLoaded", function(){
        let loc = window.location.href; 
        if (loc !== "https://mywebsite/page/somepage") { 
            setTimeout(function() {
              customModel.classList.add("model-open");
          }, 500);
        }
        
        
    });

How I can show the popup just twice per session? Thanks in advance!