We have found a strange error while installing new SAP license. my SAP license got expired. SAP* is only the user who is able to login into system and install the new sap license in slicense tcode.We are unable to install the new license. We have raised the issue to SAP, SAP suggests that first delete the old license then install new one, unfortunately SAP* also not able to delete the expired license. We gone through this SAP note 917936 to resolve the issue but this note is not applicable for us as we are on higher SP level as given.
Install the license through OS level. (saplicense)
Prerequisites
The database interface library is linked dynamically as of Release 4.5A. For saplicense to find this library, the following variables must be set in the environment of the user calling saplicense:
dbms_type = <database type> (for example, ora , inf , ada , mss , db2 , db4 , db6 )
DIR_LIBRARY = <path to dynamically linked database library> (for example, /usr/sap/SID/SYS/exe/run )
You must be logged on as the <sapsid>adm user. This ensures that all of the required environment variables are set correctly.
saplicense -show                     Display all SAP license.
if it’s not working then also check your database connectivity by R3trans -d.
saplicense – delete
First enter the SAP System ID. saplicense then asks you for the hardware key (11-character hardware key).
Enter the hardware key.
saplicense then asks you for the product ID (a name beginning with “R3_”) that indicates the database type (for example, R3_ORA).
Enter the relevant product ID for your SAP System.
The licenses are then deleted. This is confirmed by the message: saplicense: license deleted
saplicense -install  (This license can be provided manually or by file)
Please refer :
http://help.sap.com/saphelp_470/helpdata/en/a7/512c88407a11d1893b0000e8323c4f/content.htm
Source: help.sap.com