You can play for as long as you want as a guest but it means your game will be limited to a specific device. You will only play as a guest if we are unable to find a Google Play or Apple Game Center account (depending on your device).

To be able to play on multiple devices you should link your account to FACEBOOK. To do this please use the following steps:
1) From the HOME menu, tap FRIENDLY
2) Tap the CONNECT button
3) Login to your facebook account

Your account will now be automatically linked to your Facebook profile, meaning you can play across several devices