In this game there are those "special ones" worth keeping... I wind up naming my stadia after the ones I keep whole career.
They need to play almost every match and a extra training to keep up Q. On my no money teams I play 'em every match.
Here's one from a team that I occasionally watch videos for T on and also hasn't always promoted:

long term players-vv.jpg

And another, he's retiring after this season >sniff<

long term players-jan.jpg

Mostly players last about five seasons on my teams (excluding BvB where I do a lot of training they stay longer)