To check your current Testimony version on the Central System, go to the Testimony transaction and choose Overview —> Version Info:
This will show the current version, as well as the base version transport that was applied on the Central System:
To check which Cumulative Patch level your Central System is on, go to the import overview for the Central System in STSM and display all Testimony transports. (These begin with P24K*.)
You can check the source and target system version and cumulative patch level by looking at the STMS import history, again looking for P24K* transports.