I'm worried that trainer will not work & Is it safe / legal to use trainers ?

Will it work ? 

If you are worried that trainer might not work, we assure you that everything we sell on our Store is 100% working and checked, however you must make sure you have correct version of game. Some people have rushed into things, bought a trainer and then they complain "OMG IT DOESN'T WORK!", but after checking into their complaint, we quickly found out the problem > they had incorrect game version and they did not read the description.  If you are unsure, send us support ticket regarding specific product and we will give you more information (everything is listed in description anyway).

Is it safe to use trainers? 

depends how you define "safe" to use. You can get banned for using online hacks / cheats, YES.
our trainers are 100% undetectable for the anti-hack systems (unless stated otherwise in trainer description), but there is always a chance that moderator / administrator sees you use the trainer (like driving on super speed, jumping ..etc) and bans you manually, based on what they see.

If you mean, is it any danger to your computer ? absolutely not. Trainer does not make changes to any game files, it only modifies game data that has been loaded into RAM. Every time you quit the game, changes will be reset. However if you change some stats, such as money, then in some games such changes can be saved into your savegame and become permanent.

Is it legal to use trainers? 

I have no idea, but I have never in my life heard that someone gets a lawsuit for using a game trainer. You must read legal agreement from game developers to see what is allowed and what isn't. Most game companys would say no, it is not legal to modify our game, but trainer does not modify any of the game files, it makes changes in RAM, which is something else.
Once again, I haven't heard or seen any case where someone gets a lawsuit because of using trainer in an online or offline game. Think of trainer as if you would buy a real car and company says "you're not allowed to modify or paint the car", but instead you take a picture of the car and then modify / paint the picture, that's completely different story.

I heard that Blizzard Entertainment takes online cheating very seriously and that they have sued some of the hack makers, but as far as i know, they have never sued person who uses trainer / hack online.

Also i would like to bring out the fact, that game companies do not really care about online or offline cheating. They do implant anti-hack systems, but that's about it. Here is example:
If you know that "TDU 1" had lot of online cheaters and now comes game "TDU 2", would you say "oh fuck this" and not buy it? I don't think so .. 99% of people would still buy it, despite the fact that previous part of game had serious cheater problems. Therefore game companies do not care, they still get their money.

However if it comes to cheats that give you some kind of online money, like in GTA 5 online if you use money hacks, then there's a very high chance you will get banned quite fast, that's all the game companies care about, if it comes to real money, then you can get banned quite fast. Same in The Crew, we made a trainer to add money and they patched it very fast (even tho no bans were involved).

NOTE - we do not take any responsibility if you get into some kind of trouble for using our trainers, use at your own risk.