A cracked compiler can introduce silent compilation errors, miscalculate stack pointer offsets, or miscompile interrupt service routines (ISRs).
if you have an older license, contact IAR support. They often provide paths to upgrade to v8.30 at a reduced cost. iar embedded workbench for 8051 v830 hot crack updated
IAR offers a free "KickStart" evaluation version of the 8051 workbench. A cracked compiler can introduce silent compilation errors,