Sounds like you're new to After Effects.
You should understand that possession of a template DOES NOT guarantee success in AE. Templates assume that you have a good basic to intermediate knowledge of the application. If you don't, you'll get lost. In which case, you should go here: Getting started with After Effects (CS4, CS5, CS5.5, CS6, & CC)
If you've already tried a template and it won't open, you could have a version of AE that's older than the version in which the template was created. If you're unable to discern that, you should probably go here: Getting started with After Effects (CS4, CS5, CS5.5, CS6, & CC)
And before you go buying a template and downloading the AE CC tryout, you should 1) know the AE version in which it was created and 2) know if your machine is capable of running the newest version. The newest CC version will read project files created in AE CS 5 (aka Version 10), I believe.
Thanks for the response, very appreciated.
My After Effects version is CC (the trial version) and I would like to know if there's a diference between the normal version and the trial one. And also, do you think that the following template would work normally?: After Effects Project Files - Sport Motivation Promo | VideoHive
What do you mean by "something goes wrong". We can't really help you with that stuff without further information.
To answer your question, the trial version of AE is not limited.
That being said, what problems you've been having with other templates might be the same with this paid-for template, but we can't know because you haven't given us enough info.
Also, pay heed to what Dave says. The link he gave you (twice) is a very good one for someone new to AE. There are tons of "gotchas" that will come and bit you if you don't get a foundation in how the software works. For example, when you want to preview what you have in your After Effects composition, what button do you press? If you answered, "spacebar", then you DEFINITELY need to click that link.