Keil Build

Hi.

I use keil to compile a simple program, the program is as follows.

      #include "stm32f10x.h"

     int main()
    {
    while(1)
    {

    }
    }

Prompt the following error.

ArmClang: error: Failed to check out a license.Keil Licensing error: Support expired. New Product Serial Number (PSN) required
ArmClang: note: Check that your license details are correct in the License Management dialog of MDK. Additional information is available at:
www.keil.com/.../license_management.htm
If you need further help, provide this complete error report to your supplier or license.support@arm.com.
- ARMLMD_LICENSE_FILE: unset
- LM_LICENSE_FILE: unset
- ARM_PRODUCT_DEF: unset
- ARM_PRODUCT_PATH: unset
- ARM_TOOL_VARIANT: unset
- Product location: D:\keil\ARM\sw\mappings
- Toolchain location: D:\keil\ARM\ARMCLANG\Bin
- Selected tool variant: mdk_std
ArmClang: note: - Checkout feature: LIC0=KA...-.....-.....
- Feature version: 5.0202103
- Keil error code: 1
Product: MDK Plus 5.35
Component: ARM Compiler 6.16
Tool: armclang [5dfeb700]

Hope you can help me. Thanks.