Instalex is a beautiful concept, I'll be honest. I shall not detail its working or comment on its user interface because that information can be found anywhere. What I DO intend on telling you here is whether or not is this site a scam.
The answer is not a simple Yes or No, however. The truth is, the developers are TRYING their best to genuinely provide customers with what they promise. Unfortunately, they are up against a giant, giant multinational corp., Instagram, while they themselves are a small group of less than a handful of lads from Russia. The result? Most of Instalex's features (including the most important one, Auto-Like) do not work for days and days if Instagram as much as makes a TINY change in its security (which it very frequently does), before the Instalex team finds a way around it.
Verdict: Instalex is still growing. Finding ways around Instagram's security. My opinion is: Give them time. Come back after a few months. And THEN maybe give them your money.