Migration of WebMethods, will it affect source, Target, Java and Database?

We are migrating WebMethods 4.6 to 6.5 version. Please suggest me anything will affect source, target, Database and Java.
Source: SAP
Target: Elemica (Third party tool) and suggest me the following
The present 4.6 Version RAM size is 524MB,
Is this memory size enough for migration or we have to increase the size (In installation guide RAM size mentioned as 2GB for 6.5 version).

Ashok kumar.G