Hello, i am confused that whether unity pro is 1500 dolars or 75 per month.It says that in terms of this offer we need to pay 75 dolars for 12 months which is a one year license right?After that could we buy the license for 75 dolar any time i want or do i need to go for another 12 months period? Also what is the difference between this offer and 1500 dolar one? If i pay 1500 dolars is that for a one year licens or whole life for that version of unity 3d? As well as i just downloaded the latest unity 3d version with free trial but the trial version of it is closed i cannot select it, it says this option is disabled,then what is point of saying that there is a trial version?
You have to be careful. The $75 per month is a subscription, not a “deferred payment”. You simply have to pay the $75 each month as long as you use Unity pro. You have to pay for a minimum of 12 month (which is $900). If you use Unity pro that way for 3 years you would pay $2700 in total but you still don’t own the license. Once you stop your subscription the license is gone. Once the 12 month have passed you can stop the subscription at any time (as far as i know).
On the other hand if you actually buy the license you own the license. A license usually belongs to a certain major version (3, 4, 5, …). At the end of the 2.x cycle they didn’t sell 3.x licences anymore. A license is always “backward compatible” that means with a 4.x pro license you should be able to install Unity 3.x and also have pro.
If you own a license you can buy an upgrade to the newer version. In the past it was half the price of the new license. So an upgrade from 3 to 4 was $750
Keep in mind: “This information is supplied without liability.” 
Obviously it’s better for you to buy the license.
The reason Unity came up with the “subscription” is to make more money for unity.
(They didn’t sit down and say, “oh, how can we lose more money??”)
Simply do the figures and you can see the break-even point, where it is far cheaper to buy the license.
Don’t forget you have to PAY FOR EACH NEW VERSION of unity (3, 4, 5 etc) BUT THAT IS MUCH CHEAPER if you already own the license.
It’s also worth remembering that
#Unity is 4500 bucks, not 1500
.
because other than a handful of specialists who build simulators or whatever, you’re going to need to make mobile apps.
Note …
“After 12 months i can pay for 75$/month any time i want right? So for example if developments goes for 3 months”
That is completely wrong. You have to pay every month for the rest of your life - until you die.
(It might sound like an exaggeration, but that’s the reality.)
You can’t “on/off” a subscription.
The answer to your question depends on how long you are going to develop with Unity, and how much money can you afford to pay for it up front.
If you plan on developing for less than 2 years, and you need to be up to date with current version of Unity - you can definitely go with the Subscription, it will probably be cheaper:
Unity grants you license per version, versions are released every 2 years on average. If you happen to get the license when a new major release is made - great, you will have more than 2 years without making any payments to stay up to date. However if you happen to get the license in the middle of the term, it’s possible you will have to upgrade much sooner.
2 years of development using subscription model: $5400 vs $4500 for the license of a single version [which could require upgrade much earlier than 2 years].
If you plan on working with Unity for longer than that, it’s money-wise to get the license upfront, if you can handle the cost.