Check in your Zimbra Admin console: Global Settings (on left) > License (tab on right)
This will list your license type, issue date, company, expire date, all the pertinent details. If they are not correct, definitely call your Zimbra Rep. Also during the trial, the Zimbra Tech Support is very helpful to get it set up prior to purchase. I had a similar issue a couple years back, prior to my company's purchase.
Mail | Dell 2950III | 2x Quad Core 5420 | 8gb RAM | 6x 146gb SAS RAID 0+1 | Red Hat 5.3 | Zimbra 6.0.10 Network Edition
Test | VMware ESXi Whitebox | Phenom II Black 3.2ghz | 12gb RAM | 6x 1tb SATA RAID 0+1 | CentOS 5.4 | FOSS, Not in use now