The useful life of a leased asset is either:

• the estimated remaining period, from the commencement date of the lease term over which the economic benefits extractable from the asset are expected to materialize and be used by the owner (whether one user or more). The owner can consume these benefits over the useful life which is not limited to that part of the lease term, but can also extend beyond it; or
• the number of production units expected to be obtained or extracted from the use of the asset by the lessee.