My recollection is that the SO Feature is available even if you don't apply the license, although they will catch up with you when IBM does an audit. One reason for that may be because it would be too difficult to remove the license if any tables and indexes are already compressed (if the license were enforced real-time). Considering that typical CPU utilization will skyrocket with compression, and most people pay for DB2 based on CPU cores installed on the database server (PVU's), IBM should be giving SO Feature away for free.
You could easily test this by creating a test table with compression, even before you apply the license.
M. A. Feldman
IBM Certified DBA on DB2 for Linux, UNIX, and Windows
IBM Certified DBA on DB2 for z/OS and OS/390