I like the idea of 24 years plus the possibility of an extension with a fee, or proof of activity, for another 12 years if the owner is a person.
If, at any point, the rights are sold, passed, or the owner is not a person (but for example a corporation or association) it should last 12 years from that time with an extension of 6, so the ability to sell your idea or give it to your spawns for a soft landing is not destroyed, but it can not be abused.
To further avoid abuse if it has already been extended before being sold it should last only 6 years without possibility of extension. So at most it would be 42 years for active and valuable things.
EDIT: To clarify, if it gets sold multiple times, the “timer” shouldn’t be reset but keep ticking down from the date of the first transaction, or it would open the door to accounting shenanigans just to keep it alive and locked.
Let’s go with a great classic:
Prompt
Made in ComfyUI
Model: SDXL Yamer’s Anime
vae: sdxl_vae.safetensors
Prompt:
Masterpiece, A sad anthropomorphic sloth working in a cubicle, tie and shirt, elegant trousers, employee, frowning
text, watermark
Seed:
217690652583363
Empty Latent 1216 x 832, clip_scale 2.0
KSampler: 22 steps, 6.5 cfg; euler, normal
Overall a pretty vanilla generation.