You can use the db2move command (or do db2look for the DDL and export the individual table data) to the new system, since a DB2 database backup taken from DB2 for Linux cannot be restored onto DB2 for Windows.
However, you must first reinstall the DB2 Linux trial code to be able to do the db2move or db2look or export. If you don't have a backup taken before the trial license expired, you should be able to re-catalog the databases that previously existed after you reinstall DB2 for Linux. If you have a DB2 for Linux database backup, then you can just restore it onto a new database when you reinstall the DB2 trial code.
The details of these tasks are a bit too complicated to provide you with the exact syntax of every step, so if you need some help, think about using a consultant who can help you.
M. A. Feldman
IBM Certified DBA on DB2 for Linux, UNIX, and Windows
IBM Certified DBA on DB2 for z/OS and OS/390