Vimeo shows patience and wisdom with the level of gentle finesse they use to nudge you toward the upgrade to pay level. It comes with a very minor inconvenience that can be ignored forever by those who don't have a reason to go pro. This increases adoption rate. However, this same "minor inconvenience" costs money, if the user is at the pro level where it is most likely that time is money. Along with the freeing up of this inconvenience comes service bumps to further empower anyone making money with the service.
The intelligence behind this approach follows two major rules:
RULE 1: Ask for money where the money is.
If a user isn't making money with your service, then you are a cost, and you'd better be damn worth it. If they are making money with your service, then you are an investment. Keep your expense well below the earn and you will not get dropped until you let your competition out perform you.
RULE 2: Make the jump across the free-to-pay gap well worth it, easy, flexible and schedule free.
Don't pin a user to 30 days to try your app, where at the end of that evaluation they have to dump you or pay up. They'll dump you 98% of the time.
Let their company or professional growth carry them into your pay program at their own pace. Keep them as a loyal, happy user until they grow out of the features of the free level and into the pay level. Make the features very appropriate and friendly at both levels so it's a no-brainer that it's time to roll into your paid program because it's the obvious and most valuable choice.
When your service helps make or save them money, your price point is nestled into that value, your features are fitting to the needs at their level, without a no-man's-land in between the two. It should be obvious.
Also, let them roll their status forward and backward without destroying their data, their configuration, or their stats. This will let them choose a lower plan at slow business times, while easily rolling back into an active pay level when business picks back up.