Company owns & markets an old software product. Was the first of its kind, fully home grown, no long term future. But will still sell decently for probably 3-5 years. Proprietary nature precludes re engineering, so is architecturally static. No true R&D possible, though can be improved in marginal ways, which clients like. So, exactly how would this product be classified as a business asset, from the perspective of management/accounting?