[Help] GSM providers

I purchased a vehicle monitoring software and now I need to connect the devices to the main software server. I've never used a GSM, I don't know what it is and I don't know how to connect it.
can I buy a simple SIM card and activate a subscription? (so will I have to buy 50 SIM cards with 50 subscriptions?) Or are there other providers? I'm sorry but I want to understand.

any of you if you can help me send me a PM or can reply on this thread.

1. We dont know what software you bought.
2. We dont know what devices you are talking about.
You can really expect accurate answers without giving more details.
My guess would be 50 sim cards with 50 subscriptions but it may be more complicated.
Overall each gsm device that monitor something need separate sim card.

Damn mate, using Google is too hard or what? GSM simply stands for Global System for Mobile. Your smartphone is GSM. We used to call the mobile phones "GSM" not so long ago.
Anyway - look for prepaid sim cards - those come in 5-10 EUR per year, get 50 of them, use them for your software. Pretty much thats it.