How do the license tiers work?

I have two questions regarding the new license tiers on fab.

  1. If you are making less then 100k and buy asset assets under the personal license tier, but then later on make more than 100k, would you retroactively have to upgrade all used asset licenses?
  2. What does reference and source assets mean?

Standard License under a Personal - Reference Only tier: you may access the Content as a reference asset only
Standard License under a Personal or Professional tier: you may access the Content as both a source asset and a reference asset

Would I be able to e.g. retarget animations under the personal license? Or could I make some changes to props or something under the personal license?

Maybe someone can clarify this.