MG Rover's former owner BMW, which retains rights to the brand name, has revealed it would not extend a current royalty-free perk to an alternative buyer.
The German car giant said if a deal was not struck with Chinese car maker SAIC, a future contender would be expected to pay to use the Rover name.
The news comes after SAIC said it was "not interested" in further talks while Longbridge remained in administration and speculation grows over other buyers for the plant.
A spokeswoman for BMW said: "If it was a new organisation or company approaching us outside any company that is currently involved in MG Rover we would need to be looking at royalty for the licence.
"It would be a full contractual agreement at that point."
BMW retained the rights to the Rover name when it sold the company to the Phoenix consortium in 2000 for £10.
As part of the deal, it agreed not to charge royalties on the licence. The same conditions were extended during talks with Shanghai-based SAIC.
"We own the rights to the Rover name," a spokeswoman said. "That means it can only be used by people other than BMW through the issue of a licence.
"While the joint venture negotiations are on-going we don't see putting any hurdles in place for the future use of the Rover name as helpful to those talks.
"But if anyone wanted to use the name outside that they would have to contact us and the normal negotiations would take place."
The company refused to speculate on how much the brand name is worth in terms of royalties.
"We don't have a value at this stage because there hasn't been a need to put any value on it for the last five years," said the spokeswoman.
Rover's continuing obligation to BMW could serve to put off some future buyers. Blackpool-based sports car maker TVR, owned by Russian financier Nikolai Smolensky, has been suggested as a possible candidate if the China deal falls through.
But the company denied it had any interest in taking over MG Rover.
A spokesman for the firm said: "I heard a rumour this morning that Nikolai was going to sell TVR to a Welshman.
"It is all rubbish - he is committed to TVR and that is as far as it goes."
An alternative buyer for MG Rover would also face taking on its £427 million loan with BMW.
The current owners have the loan on an interest-free basis while the firm is not making profit.