Yes, the number of allowed uploads per project depends on your subscription plan:
Free projects:
10 images,
3 videos ( up to 100MB and 20sec each),
3 audiosCreator projects:
10 images,
5 videos (up to 500MB and 40sec each),
5 audiosPro projects:
50 images,
50 videos (up to 1000MB and 120sec each),
50 audiosAgency projects:
150 images,
100 videos(up to 1000MB and 120sec each),
100 audios