Can I change plans at any time ?
You may upgrade or downgrade leased license seamlessly and instantly at any point of time without reinstalling.
Can I upgrade from free license to leased plan as i have more than 5 servers?
Yes. You may upgrade free license to leased seamlessly without having to reinstall.
Is there any limit for the free license ?
Free license is available only on a monthly basis for 5 servers. That is, you need to manually renew every month. And you can purchase only one free license. Other than that, there are no limits. Free secondary license is also available with the free license.
How much will it cost for 6 servers since i get 5 server for free?
Once your license goes from 5 free server to 6 servers, the cost would for the entire 6 servers which would be 6 servers * $2 = $12 /per-month.