The Uniswap v4 code is licensed under a combination of a Business Source License (BUSL) and MIT License.
The BUSL limits the use of the v4 source code in a commercial or production setting until June 15, 2027, at which point it will convert to a MIT license.
Like Uniswap v3, Uniswap Governance can grant exceptions to the BUSL via Additional Use Grants.