If you regularly visit the same airports you should check and see whether it'd make more sense to just pay an admission fee there and then as opposed to tying yourself up for the whole year. Three airport lounges I've been in recently (BHX, PRG, WAW) welcomed anyone willing to part with 20-25 Euros for a drink and a newspaper.
Of course the above doesn't make a lot of sense if you travel frequently enough to be able to make economic use of their unlimited level, in which case you probably should already have free access by being elite with some airline or another.