Ideally you capture information in your initial call about timeline, budget (do they have budget already approved and ready, or are they getting quotes so they can get budget), and critical decision making factors.
For security systems I think it is safe to assume most buyers intend to make a purchase within 3 months for an average to small system, and somewhere around 6-9 months for larger systems. Larger systems are more likely to have to go through more product evaluation and budget approvals, thus the longer timeline.
If your prospect has been responsive over several calls, and then goes dark for a period that is ~2x the decision time (so, 6 months for a small system, ~1 year for a larger system) you can mark it as "Closed/Lost".
However, part of a good sales management process is "lead nurturing". I think even if you are assuming it is a lost opportunity it can make sense to followup in a year. Maybe the previous decision maker left the company, and now a new person is in place and picking up the project. Maybe their previous budget got cancelled and they just didn't like answering pesky sales people, but intended to purchase something later. Maybe they purchased your competitors product but are now unhappy with it and want to switch vendors before going into a 2nd deployment phase.
This is where automatic emails, things like newsletters and updates can be valuable to do a "soft sell". You don't need to ask "Hey, are you going to buy this yet?!?!?", but you can remind them your company exists and has potentially released some new widget.
Companies with larger sales staff may also use inside sales for part of this role, making followup calls every few weeks to try and reach the buyer and get a definitive answer on why the sale never closed.
There are some schools of thought that you never really "give up", you just keep gently pursuing them until they decide to buy. In the past I have had leads that took 3+ years to close, some with significant periods of no communication in the middle, or customers that went with a competitor and then finally came around and realized that was a bad idea.
In your case the 1 year followup roughly makes sense, many providers may ask for a 1 year commitment. The salesperson might have been calling assuming you went with another option, and now after a year may be in a position to reevaluate your previous decision.