Dear Sina Jan,
Yes, You need to import License file with in 30 days as initially 30 days is Trial Period. If Trial Period expired and there is no License File then you will not be able to use SAP.
If you have created New Company then that Company Database is empty, there is no sample data in New Company database.
If you are looking in Demo Company of SAP then you will find Master Data as well as Transaction also.
Please create New Company for your Client. Demo database is for reference.
Manager is default user in SAP B1 so you have to create 4 users for your client in New Company. Manager user is for Implementation Purpose.
Please check below link for more information's.
http://help.sap.com/saphelp_sbo882/helpdata/en/b1/8fe14910cf46b9b2ff2de2f315e5a2/frameset.htm
Study Material for SAP Business one 8.81
Hope this help 
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Regards::::
Atul Chakraborty