diff --git a/Readme.md b/Readme.md
index 3edb50d..9b6720f 100644
--- a/Readme.md
+++ b/Readme.md
@@ -56,7 +56,8 @@ const CONFIG = {
   overwrite: true, /** (boolean) can overwrite or not (default true) */
   httpOnly: true, /** (boolean) httpOnly or not (default true) */
   signed: true, /** (boolean) signed or not (default true) */
-  rolling: false, /** (boolean) Force a session identifier cookie to be set on every response. The expiration is reset to the original maxAge, resetting the expiration countdown. default is false **/
+  rolling: false, /** (boolean) Force a session identifier cookie to be set on every response. The expiration is reset to the original maxAge, resetting the expiration countdown. (default is false) */
+  renew: false, /** (boolean) renew session when session is nearly expired, so we can always keep user logged in. (default is false)*/
 };
 
 app.use(session(CONFIG, app));
diff --git a/lib/context.js b/lib/context.js
index 77095ad..df162ee 100644
--- a/lib/context.js
+++ b/lib/context.js
@@ -207,7 +207,6 @@ class ContextSession {
 
   async commit() {
     const session = this.session;
-    const prevHash = this.prevHash;
     const opts = this.opts;
     const ctx = this.ctx;
 
@@ -220,24 +219,47 @@ class ContextSession {
       return;
     }
 
-    // force save session when `session._requireSave` set
-    let changed = true;
-    if (!session._requireSave) {
-      const json = session.toJSON();
-      // do nothing if new and not populated
-      if (!prevHash && !Object.keys(json).length) return;
-      changed = prevHash !== util.hash(json);
-      // do nothing if not changed and not in rolling mode
-      if (!this.opts.rolling && !changed) return;
-    }
+    const reason = this._shouldSaveSession();
+    debug('should save session: %s', reason);
+    if (!reason) return;
 
     if (typeof opts.beforeSave === 'function') {
       debug('before save');
       opts.beforeSave(ctx, session);
     }
+    const changed = reason === 'changed';
     await this.save(changed);
   }
 
+  _shouldSaveSession() {
+    const prevHash = this.prevHash;
+    const session = this.session;
+
+    // force save session when `session._requireSave` set
+    if (session._requireSave) return 'force';
+
+    // do nothing if new and not populated
+    const json = session.toJSON();
+    if (!prevHash && !Object.keys(json).length) return '';
+
+    // save if session changed
+    const changed = prevHash !== util.hash(json);
+    if (changed) return 'changed';
+
+    // save if opts.rolling set
+    if (this.opts.rolling) return 'rolling';
+
+    // save if opts.renew and session will expired
+    if (this.opts.renew) {
+      const expire = session._expire;
+      const maxAge = session.maxAge;
+      // renew when session will expired in maxAge / 2
+      if (expire && maxAge && expire - Date.now() < maxAge / 2) return 'renew';
+    }
+
+    return '';
+  }
+
   /**
    * remove session
    * @api private
@@ -264,7 +286,7 @@ class ContextSession {
     const externalKey = this.externalKey;
     let json = this.session.toJSON();
     // set expire for check
-    const maxAge = opts.maxAge ? opts.maxAge : ONE_DAY;
+    let maxAge = opts.maxAge ? opts.maxAge : ONE_DAY;
     if (maxAge === 'session') {
       // do not set _expire in json if maxAge is set to 'session'
       // also delete maxAge from options
@@ -278,6 +300,10 @@ class ContextSession {
     // save to external store
     if (externalKey) {
       debug('save %j to external key %s', json, externalKey);
+      if (typeof maxAge === 'number') {
+        // ensure store expired after cookie
+        maxAge += 10000;
+      }
       await this.store.set(externalKey, json, maxAge, {
         changed,
         rolling: opts.rolling,
diff --git a/package.json b/package.json
index 674c0aa..3a61042 100644
--- a/package.json
+++ b/package.json
@@ -20,6 +20,7 @@
     "koa": "2",
     "mm": "^2.1.0",
     "mocha": "3",
+    "mz-modules": "^2.0.0",
     "should": "8",
     "supertest": "2"
   },
diff --git a/test/store.test.js b/test/store.test.js
index b582d4e..9943ffb 100644
--- a/test/store.test.js
+++ b/test/store.test.js
@@ -8,6 +8,7 @@ const session = require('..');
 const store = require('./store');
 const pedding = require('pedding');
 const assert = require('assert');
+const sleep = require('mz-modules/sleep');
 
 describe('Koa Session External Store', () => {
   let cookie;
@@ -717,6 +718,57 @@ describe('Koa Session External Store', () => {
       });
     });
   });
+
+  describe('when renew set to true', () => {
+    let app;
+    before(() => {
+      app = App({ renew: true, maxAge: 2000 });
+
+      app.use(async ctx => {
+        if (ctx.path === '/set') ctx.session = { foo: 'bar' };
+        ctx.body = ctx.session;
+      });
+    });
+
+    it('should not send set-cookie when session not exists', () => {
+      return request(app.callback())
+      .get('/')
+      .expect({})
+      .expect(res => {
+        should.not.exist(res.headers['set-cookie']);
+      });
+    });
+
+    it('should send set-cookie when session near expire and not change', async () => {
+      let res = await request(app.callback())
+      .get('/set')
+      .expect({ foo: 'bar' });
+
+      res.headers['set-cookie'].should.have.length(2);
+      const cookie = res.headers['set-cookie'].join(';');
+      await sleep(1200);
+      res = await request(app.callback())
+      .get('/')
+      .set('cookie', cookie)
+      .expect({ foo: 'bar' });
+      res.headers['set-cookie'].should.have.length(2);
+    });
+
+    it('should not send set-cookie when session not near expire and not change', async () => {
+      let res = await request(app.callback())
+      .get('/set')
+      .expect({ foo: 'bar' });
+
+      res.headers['set-cookie'].should.have.length(2);
+      const cookie = res.headers['set-cookie'].join(';');
+      await sleep(500);
+      res = await request(app.callback())
+      .get('/')
+      .set('cookie', cookie)
+      .expect({ foo: 'bar' });
+      should.not.exist(res.headers['set-cookie']);
+    });
+  });
 });
 
 function App(options) {