Hi Fakhri,
This is weird because user guide of 200.7 version also says that you should get Validity period option if you choose Guest Access.

Could you follow below and confirm if this fixes the issue.
- Access the Unleashed GUI from Google chrome incognito browsing window.
- Try to give a name to SSID and then see if option comes back or not.
Regards,
Syamantak Omer
Syamantak Omer | Community moderator | Sr.Staff TSE | CWNA | CCNA | RASZA | RICXI