Well yes and no you can release them going forward under a new licence. If you obtained your copy under the old license you can use it under the old license when you obtain a new copy you have a new license agreement. Thats absolutly possible to do Revoking licenses is alot harder though and changing the lizens from a foss on to another is often confusing and business inapropiate. However it is legal.
mobotsar@sh.itjust.works 3 days ago
Assuming newer versions are derived from code that was licensed GPL in the old version, the newer versions (which include new code) are also licensed GPL, whether the person writing the new code likes it or not.
deaddigger@sh.itjust.works 2 days ago
No, this is plainly wrong. A license is a proclamation of the copyrightowner how others can use their material. The copywrite owner does not license their own work to themself, they can do whatever they want with their copyright