When the creator gave me the “unlimited right to use the underlying IP” of my NFT, can I enforce the rights against unlicensed use of third parties?

Under French law, an assignment of rights, whether these be rights to use or transfer of ownership), to be valid, requires certain formalities, essentially, the requirement of i) an agreement in writing, ii) the specification of the rights assigned that must be carefully detailed as to their nature (reproduction, representation, adaptation), the extent (in space and time), on what means/medium.

It follows that a creator who has given « full ownership rights » is not opposable under French law, in such a way that the NFT holder/owner may not be able to enforce such rights.

If it is an IP license regarding the work of the NFT, the licensee could also legally claim third parties in case of misuse, if this was declared and agreed in the license provided or if this was causing any damage to the holder.