Perpetual access refers to the right to ongoing access to electronic materials. In situations where digital materials are licensed, access to these materials is often lost after the licensing agreement has expired. In many cases, the two parties involved in the license agree that it is necessary for the license to retain access to these materials after the license has lapsed.
In the licensing of software products, a perpetual license means that a software application is sold on a one-time basis and the licensee can then use a copy of the software forever. The license holder has indefinite access to a specific version of a software program by paying for it only once.
Perpetual access is a term that is used within the library community to describe the ability to retain access to electronic journals after the contractual agreement for these materials has passed. Typically when a library licenses access to an electronic journal, the journal's content remains in the possession of the licensor. The library often purchases the rights to all back issues as well as new issues. When the license elapses, access to all the journal's contents is lost. In a typical print model, the library purchases the journals and retains them for the duration of the contract but also after the contract expires. In order to retain access to journals that were released during the term of a license for digital electronic journals, the library must obtain perpetual access rights.
Perpetual access is closely related to digital archiving, which is the preservation of electronic documents. Often, if an institution is to retain perpetual access, it must design a way in which to preserve the electronic documents that are granted by the license. Several initiatives have developed methods in which to retain electronic documents and retain perpetual access. The most notable of these are the LOCKSS program and the Ithaka Portico program.