I have been using no-ip for around two years to remotely access my hosted service, I mostly use their free service except for a few 5 months offers I bought.

Recently, I received a full year offer in email for 8$ (COUPON CODE: MAY8), and I was wondering whether to get that or buy a 2 years domain for the same price (FROM hostinger or namecheap).

I have never bought a doamain before and my knowledge is limited to what I mostly read here. So, per your opinion, what would be better in term of usability and security, a DDNS on the router and a port open per hosted-service? or a domain with reverse proxy?