Personal (one time) - Unlimited Personal Use, all features included. You may not sell prints or models, but you make give them away, however you must mark them as non-commercial.
Limited Commercial (annual) - Unlimited Personal Use (reverts to PU after 1 year if you don't renew), all features included. You may sell prints, but you may not sell digital files (you may still give away digital files marked non-commercial).
Professional (annual) - Everything that Limited Commercial has, but you may also sell digital files.
Lifetime Professional (one time) - Professional Commercial rights forever.
What is Lifetime
Perpetual usage rights (and commercial rights where applicable)
2 years of updates/bug fixes. Future