diff --git a/src/index.ts b/src/index.ts
index 00ec097..0e8ceac 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -12,7 +12,7 @@ import {
 } from './main';
 import { SplitTest } from './splitTest';
 import { uiFactory } from './ui';
-import { UserSessionPersister } from './userSessionPersister';
+import { UserSessionPersister, InMemoryPersister, CookiePersister } from './userSessionPersister';
 
 const ui = uiFactory(
     testsObservable,
@@ -49,6 +49,8 @@ export {
     ui,
     SplitTest,
     UserSessionPersister,
+    InMemoryPersister,
+    CookiePersister,
 };
 
 export default {
diff --git a/src/main.ts b/src/main.ts
index dd4be4b..0c44bd0 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -31,7 +31,9 @@ export function config(userConfig: Partial<Config> = {}) {
         _config.onVariationChange = userConfig.onVariationChange;
     }
     if (userConfig.sessionPersister) {
+        const userSession = _config.sessionPersister.loadUserSession() || '';
         _config.sessionPersister = userConfig.sessionPersister;
+        _config.sessionPersister.saveUserSession(userSession, _config.userSessionDaysToLive);
     }
 }
 
diff --git a/src/userSessionPersister.ts b/src/userSessionPersister.ts
index 41a18a2..679503a 100644
--- a/src/userSessionPersister.ts
+++ b/src/userSessionPersister.ts
@@ -1,40 +1,46 @@
 import config from './config';
-
 export interface UserSessionPersister {
     loadUserSession(): string | null;
     saveUserSession(userSession: string, daysToLive: number): void;
 }
-
-function createCookie(name: string, value: string, days: number): void {
-    let expires = '';
-    if (days) {
-        const date = new Date();
-        date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
-        expires = '; expires=' + date.toUTCString();
+export class CookiePersister implements UserSessionPersister {
+    public loadUserSession() {
+        return CookiePersister.readCookie(config.cookieName);
     }
-    document.cookie = name + '=' + value + expires + '; path=/';
-}
-
-function readCookie(name: string): string | null {
-    const nameEq = name + '=';
-    const ca = document.cookie.split(';');
-    for (let c of ca) {
-        while (c.charAt(0) === ' ') {
-            c = c.substring(1, c.length);
+    public saveUserSession(userSession: string, daysToLive: number) {
+        CookiePersister.createCookie(config.cookieName, userSession, daysToLive);
+    }
+    private static createCookie(name: string, value: string, days: number): void {
+        let expires = '';
+        if (days) {
+            const date = new Date();
+            date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
+            expires = '; expires=' + date.toUTCString();
         }
-        if (c.indexOf(nameEq) === 0) {
-            return c.substring(nameEq.length, c.length);
+        document.cookie = name + '=' + value + expires + '; path=/';
+    }
+    private static readCookie(name: string): string | null {
+        const nameEq = name + '=';
+        const ca = document.cookie.split(';');
+        for (let c of ca) {
+            while (c.charAt(0) === ' ') {
+                c = c.substring(1, c.length);
+            }
+            if (c.indexOf(nameEq) === 0) {
+                return c.substring(nameEq.length, c.length);
+            }
         }
+        return null;
     }
-    return null;
 }
-
-export class CookiePersister implements UserSessionPersister {
+export class InMemoryPersister implements UserSessionPersister {
+    private endOfLife: number = 0;
+    private storage: string = '';
     public loadUserSession() {
-        return readCookie(config.cookieName);
+        return !this.endOfLife || (Date.now() > this.endOfLife) ? '' : this.storage;
     }
-
     public saveUserSession(userSession: string, daysToLive: number) {
-        createCookie(config.cookieName, userSession, daysToLive);
+        this.storage = userSession;
+        this.endOfLife = Date.now() + (daysToLive*24*60*60*1000);
     }
-}
+}
\ No newline at end of file