Villagers don't lose their professions if they have been leveled up to Apprentice or higher.

I'm certain that this is how it should work: Once you have traded with a villager enough, it will keep its job.

Even if you broke his workstation? They will never restock and will never change proffesion. Sometimes they randomly lose interest in working on their workstation and start acting as a nitwit, which leaves the workstation 'unemployed' and gets another villager interested to take the same job which already exists. The difference is, that one of the villagers will work and restock during the day and follow the schedule and the other is that the villager will never change his proffesion he will act as a nitwit (even if he's not), sometimes doesn't go to bed during the night and leaving him totally unresponsive during the night and day(unless a zombie aproaches him).

This relates to MC-150777. There is actually a comment from @slicedlime in MC-150777 that states this is also intended. If you trade with a villager then it keeps its profession forever (even if it is still novice level).

Ok I undestand, the problem is that when the villager loses his proffesion (by breaking his workstation for example) and when you place the appropriate workstation back he doesn't go to that worksite again to keep working on THE SAME proffesion. Meaning if the player trades with all of the possible trades and the villager runs out of stock, what's the point of that villager after that? Another thing is that while some of the villager whom are working they sometimes randomly decide to not go to work on their workstations and keep their trades and let another villager take their place (even if the workstation hasn't been destroyed). I'll upload a screenshot as a simple example.
 

On this picture it shows that there's two Weaponsmiths. But only one grindstone in the village, and for some reason there's two of them now when there should be only 1.

This looks like MC-150806 but with steps to reproduce in the comments.

There are no comments on the issue :I

Villagers that lost interest in their worksite really like to hang out near the village boundary for some reason and not attend in meetings (the meeting areas). Sometimes they just sit outside and do nothing like they have no AI and swim on water and stay on it like back in Minecraft Alpha. Sometimes I try pushing them out from the water but they want to go back in and sit on that one specific block for no reason, when they should be working, sleeping, meeting in the central area.

I was refering to MC-154415 (your ticket) as having steps to reproduce in the comments, as there are no steps to reproduce in MC-150806 (which may change).

And villagers refusing to work, sleep, and gather is a different issue.

The picture with the Stone Mason shows that he is supposed to be in the meeting area right next to the big birch area ahead (on the left). He doesn't go to the meeting area but he's employed and works on his workstation (the stonecutter). Sometimes he goes to the meeting, sometimes he doesn't.

I had a case when I built a Library for this village and employed 2 nitwits to become Librarians, one of them had a Fortune 3 book, I traded with him and I left the village and went to my own base.

Sometime later I come back, the expirience bar is empty and there are completely new trades, now he had a flame enchanted book. The other librarian I traded with stayed the same and he kept working on the Lectern I placed for him. I played today again and I see the villager who changed his trades (the librarian) not working next to his other librarian villager, but he talks with other glitched employed villagers during the day. Note that no other villager took his place as a Librarian.

Sorry 😛

I think this is working as intended, as they were trying to prevent people from breeding a villager, finding that oh, this guy has mending for 21 emeralds! And then trading that, only to find one with a cheaper price and deciding to reuse that villager. Sorry if not correct, but just my thoughts 🙂

@Joseph_Landis Im genuinely confused from your comment. I don't think that has to do anything with this issue? Also, no one mentioned breeding.

lol thanks mod i was very nervous when I was creating this issue. That's why most of my comments are edited 

Works as intended?

DockWonder, read the issues that this feature brings in the comments

If a villager doesn't have a workstation anymore, it's normal that he seeks for a new one wandering around, leading to him not sleeping (or meeting, etc.).

Yes but if you broke a workstation for a villager that you already traded with, he will forever look for a workstaion/job? He will never lose his profession because you traded with him, leaving him with broken AI forever?

I think the feature brings some issues regarding villager AI.

Even if the villagers not losing their proffesion is an 'intended' feautre, then why is it dofferent in Minecraft Bedrock? Ive seen gameplay and it shows that when a villager has been traded with once(but not leveled up) he still was able to switch professions.