To assign license key in vCenter Server 6.5

Please follow mentioned steps

1. Login to Virtual Center using Web or vSphere Client.
2. On top of console, you can see the note saying that licenses in our inventory either expired or not available.
3. Go to Home > Click onLicensesunder Administration Tab
4. Click on Manage your Licensesin Getting Started Tab or Go toLicensesTab.
5. Click on+icon toCreate New Licenses.
6. Enter the vCenter Server 6.x Standard license key and press Enter to add a new line.
7. Enter the vSphere 6.x Standard license key(For ESXi), and click Next.
8. Label the license keys as per your convenient. Click onNext.