I'm using Bonita Studio 7.0.1 since its release and I noticed the installation folder keeps getting bigger day after day. It is now 6GB and I'm running out of disk space (I work on a virtual machine with only 20GB).
The workspace/tomcat/bonita/engine-server/work/platform directory is the biggest one and is filled with what seems to be old instances of bonita engine : bonita_engine_@.
These folders only contains some *.jar.jar.tmp files. I assume these are some kind of temporary files left behind by the engine after it has been stopped.