Some time we need to reactive your Plesk license of your VPS or Dedicated servers. Here is method to activation your license on Linux or Windows OS
Via SSH
If you have Plesk License key
/usr/local/psa/bin/license -i XXXXXX-XXXXXX-XXXXXX-XXXXXX-XXXXXX
If you have License file
/usr/local/psa/bin/license -i /path/to/PLSK.XXXXXXXX.XXXX.xml
Via RDP
If you License Key
c:/>"%plesk_dir%\bin\license.exe" -i XXXXXX-XXXXXX-XXXXXX-XXXXXX-XXXXXX
If you have License Key
c:/>"%plesk_dir%\bin\license.exe" -i "C:\path\to\file\PLSK.XXXXXXXX.XXXX.xml"