is there stuff i retain if i subscribe for just one month?
Yes. Go for it. The preferred (ex-sub) status has several advantages over the F2P.
Don't forget to use a codexers referal before subbing, they get... dunno, a mount(?) plus some change in cartel coins! Don't waste that chance.
You get, and get to keep once your sub runneth out:
Level 75 cap
All expansions unlocked (Hutts, Revan, KOTFE, KOTET, Onslaught). That's enough depression food for two months.
Account status is set from "filthy casual f2p" to "preferred", which is far less restrictive on everything.
Protips:
If you used a referral, you get an email on each of your toon, containing a box with a few unlocks (color, inventory slot, display titles, crewskill slot). Take the box and store it in your cargo hold for AFTER the sub time. Game likes to "forget" you used them if done before/during sub.
When your sub is about to run out:
Display/hide headslots on all your toons, that option is locked for non-subs.
Same goes for legacy names.
Credit cap for non-subs is 1 million. Store everything above in your legacy bank. The game takes everything above that hostage until you resub.
This is the way, my Bounty Hunter
Ah yes, the good old hydra set. The adaptive vendor was the bestestest idea in the game. Each of the classes has at least one former rare-to-get armor now slapped in their faces for a laughable sum. The Vendetta armor ("for agents") is another example, reaaaaally nice looking ones easy to get, without having to shell out several 100k on the GTN. IF the player even knows they exist.
Ironically I went back to wearing the stuff you get from leveling, because nobody wears that anymore with all those other options. The Alderaan smuggler jacket is pretty sweet looking.