Adding A subscription for NSP for 5 devices to a current subscription

Subscription
1

I purchased and activated a subscription for NSP with Backup for 3 devices. Can I add a subscription for NSP with Backup for 5 devices?  AS I have 2 pcs, 2 tablets & one phone. If so, do I manage all devices and licences from this computer, which is my main device?

Thanks In Advance