Yes, you can upgrade to it in Members Area fully automatic. 

Dynamic IPs change on every new reconnect randomly and Country wide only, meaning on the same Country which you are currently assigned to. Depending on your choice of Country the total amount of available IPs always varies - it can be more or less - but the average is around 30-200 IPs for each Country. 

Additionally it is important to understand that a VPN is NOT a proxy Service! VPN Services almost always receive a full block of IPs from network side, NOT mixed with different Subnets. 

So in the most cases the last 3 Digits randomly changes as example: 188.121.201.147 => 188.121.201.189 => 188.121.201.75. 

Meanwhile some countries like UK/USA2/USA3 have different Subnets (example: 188.121.201.147 => 46.138.57.177) but this is an exception and not the usual case. Example video here