I am confused. I have a Reseller account with 20 domains under WebhostManager and cPanel.

Hello
I have a Reseller account with 10 domains that I own under WebhostManager and cPanel. do I use Webhostmanager's copy of WordPress available to me or do I download a separate copy of wordpress for each domain? I want multisites, memberships, prosites and other sites on my domains. What's the
best solution?