Expandable. Referring to hardware or software, the term is a popular buzzword in the IT world. A "highly scalable" device or application implies that it can handle a large increase in users, workload or transactions without undue strain.
There May Be a Price
Scalable does not always mean that expansion is free. Extra-cost hardware or software may indeed be required to handle more work. Nevertheless, scalability is a positive feature of a product that is sold to fast-growing companies, because it implies that growth can be accommodated without having to make major changes or learn new procedures. See scale