How long does Aegis last?

Excuse me, could you clarify something for me about Aegis? I'm curious to know, how long is the duration of its effectiveness or lifespan? Is it a short-term solution that requires frequent renewal, or is it a long-lasting measure that can provide stability and protection over an extended period? Understanding this aspect would greatly help in assessing its suitability for my needs. Thank you in advance for your insight.