For BPAs established under GSA schedule contracts, FAR 8.405-3(c) states that a BPA generally should not exceed 5 years; however, they may exceed the 5 years to meet program requirements. (bolding added for emphasis) FAR part and 16 do not address the duration of a BPA; however, please note that FAR 8.405-3(d), 13.303-6 and 16.702(b)(3) all require review of the basic agreement annually.
Some agencies have established procedures and best practices for the issuance of BPAs and the duration of a BPA may be limited by these internal policies.
For example, please see NASA's procurement policy which provides for a 5 year limitation on all award documents, including agreements
BPAs are not contracts; they are agreements. A Contracting Officer should always consider whether transitioning BPAs to more formal contract vehicles is in the best interests of the government. Each year, the contracting officer should review and document the strategy of using a BPA versus a contract.