Thanks David for your following up:
Actually i have some more questions:
About licensing:
Is the license a per-user license? (meaning that i can access the mail from more than one device without extra fees)??
About Data Backup:
Can i "at any point in time" download my mails to an on-premises network share "ex. to my FTP server"???
About The archiving period:
Can i apply this workaround "in-place hold" to all users in the enterprise? or easily change the default policy to be more then 5 years??
thanks again and i appreciate your answers
regards
M.Zakaria