question about netbackup deduplication license

Hello guys,

I got confuse about the netbackup deduplication license. Current, our production enviornment running netbackup deduplication options with follow license:

SYMC NETBACKUP ENTERPRISE SERVER 7.0 WIN/LNX/SOLX64 1 SERVER TIER 2 STD LIC

SYMC NETBACKUP DEDUPLICATION OPTION 7.0 XPLAT 1 FRONT END TBYTE STD LIC EXPRESS BAND S  

i can found from the admin console the puredisk option license is 1TB. So, what does it means? I can create a deduplication pool equal to 1TB or less (honestly, now we are using over 1TB pool size)? or the client backup data can not bigger than 1TB? If i am planning upgrade Netbackup with deduplication from 7.0 to 7.6 with 5TB deplulcation pool .Which licensing i need to renew/purchase? also the quantity. Thanks.