A system for protecting software against piracy while protecting a user's privacy enables enhancements to the protection software in a user device and extended protections against piracy. The protection system allows the user device to postpone validation of purchased tags stored in a tag table for installed software and to re-establish ownership of a tag table to recover from invalidation of a tag table identifier value resulting from revelation of a tag table identifier value. Continued use of the tag table is provided by the use of credits associated with a tag table. A protection center is protected against denial of service attacks by making calls to the protection center cost time or money to the attackers.